Change the DiscoveryProviderManager to use the Multiplexer logic

Fix: 263893748
Test: e2e with test app
Ignore-AOSP-First: nearby_not_in_aosp_yet
Change-Id: I8e8d540951ce5afba03b7bb66269b519d19f2f35
diff --git a/nearby/service/java/com/android/server/nearby/NearbyService.java b/nearby/service/java/com/android/server/nearby/NearbyService.java
index 8d35e08..2ac2b00 100644
--- a/nearby/service/java/com/android/server/nearby/NearbyService.java
+++ b/nearby/service/java/com/android/server/nearby/NearbyService.java
@@ -45,7 +45,9 @@
 import com.android.server.nearby.fastpair.FastPairManager;
 import com.android.server.nearby.injector.Injector;
 import com.android.server.nearby.managers.BroadcastProviderManager;
+import com.android.server.nearby.managers.DiscoveryManager;
 import com.android.server.nearby.managers.DiscoveryProviderManager;
+import com.android.server.nearby.managers.DiscoveryProviderManagerLegacy;
 import com.android.server.nearby.presence.PresenceManager;
 import com.android.server.nearby.provider.FastPairDataProvider;
 import com.android.server.nearby.util.identity.CallerIdentity;
@@ -80,18 +82,21 @@
                     }
                 }
             };
-    private final DiscoveryProviderManager mProviderManager;
+    private final DiscoveryManager mDiscoveryProviderManager;
     private final BroadcastProviderManager mBroadcastProviderManager;
 
     public NearbyService(Context context) {
         mContext = context;
         mInjector = new SystemInjector(context);
-        mProviderManager = new DiscoveryProviderManager(context, mInjector);
         mBroadcastProviderManager = new BroadcastProviderManager(context, mInjector);
         final LocatorContextWrapper lcw = new LocatorContextWrapper(context, null);
         mFastPairManager = new FastPairManager(lcw);
         mPresenceManager = new PresenceManager(lcw);
         mNearbyConfiguration = new NearbyConfiguration();
+        mDiscoveryProviderManager =
+                mNearbyConfiguration.refactorDiscoveryManager()
+                        ? new DiscoveryProviderManager(context, mInjector)
+                        : new DiscoveryProviderManagerLegacy(context, mInjector);
     }
 
     @VisibleForTesting
@@ -108,7 +113,7 @@
         CallerIdentity identity = CallerIdentity.fromBinder(mContext, packageName, attributionTag);
         DiscoveryPermissions.enforceDiscoveryPermission(mContext, identity);
 
-        return mProviderManager.registerScanListener(scanRequest, listener, identity);
+        return mDiscoveryProviderManager.registerScanListener(scanRequest, listener, identity);
     }
 
     @Override
@@ -119,7 +124,7 @@
         CallerIdentity identity = CallerIdentity.fromBinder(mContext, packageName, attributionTag);
         DiscoveryPermissions.enforceDiscoveryPermission(mContext, identity);
 
-        mProviderManager.unregisterScanListener(listener);
+        mDiscoveryProviderManager.unregisterScanListener(listener);
     }
 
     @Override
@@ -147,7 +152,7 @@
 
     @Override
     public void queryOffloadCapability(IOffloadCallback callback) {
-        mProviderManager.queryOffloadCapability(callback);
+        mDiscoveryProviderManager.queryOffloadCapability(callback);
     }
 
     /**
@@ -174,7 +179,7 @@
                     // Initialize ContextManager for CHRE scan.
                     ((SystemInjector) mInjector).initializeContextHubManager();
                 }
-                mProviderManager.init();
+                mDiscoveryProviderManager.init();
                 mContext.registerReceiver(
                         mBluetoothReceiver,
                         new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED));
diff --git a/nearby/service/java/com/android/server/nearby/managers/DiscoveryManager.java b/nearby/service/java/com/android/server/nearby/managers/DiscoveryManager.java
new file mode 100644
index 0000000..c9b9a43
--- /dev/null
+++ b/nearby/service/java/com/android/server/nearby/managers/DiscoveryManager.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.nearby.managers;
+
+import android.nearby.IScanListener;
+import android.nearby.NearbyManager;
+import android.nearby.ScanRequest;
+import android.nearby.aidl.IOffloadCallback;
+
+import com.android.server.nearby.util.identity.CallerIdentity;
+
+/**
+ * Interface added for flagging DiscoveryProviderManager refactor. After the
+ * nearby_refactor_discovery_manager flag is fully rolled out, this can be deleted.
+ */
+public interface DiscoveryManager {
+
+    /**
+     * Registers the listener in the manager and starts scan according to the requested scan mode.
+     */
+    @NearbyManager.ScanStatus
+    int registerScanListener(ScanRequest scanRequest, IScanListener listener,
+            CallerIdentity callerIdentity);
+
+    /**
+     * Unregisters the listener in the manager and adjusts the scan mode if necessary afterwards.
+     */
+    void unregisterScanListener(IScanListener listener);
+
+    /** Query offload capability in a device. */
+    void queryOffloadCapability(IOffloadCallback callback);
+
+    /** Called after boot completed. */
+    void init();
+}
diff --git a/nearby/service/java/com/android/server/nearby/managers/DiscoveryProviderManager.java b/nearby/service/java/com/android/server/nearby/managers/DiscoveryProviderManager.java
index 29b18f3..4cda93a 100644
--- a/nearby/service/java/com/android/server/nearby/managers/DiscoveryProviderManager.java
+++ b/nearby/service/java/com/android/server/nearby/managers/DiscoveryProviderManager.java
@@ -21,320 +21,74 @@
 import static com.android.server.nearby.NearbyService.TAG;
 
 import android.annotation.Nullable;
-import android.app.AppOpsManager;
 import android.content.Context;
 import android.nearby.DataElement;
 import android.nearby.IScanListener;
 import android.nearby.NearbyDeviceParcelable;
 import android.nearby.NearbyManager;
 import android.nearby.PresenceScanFilter;
-import android.nearby.ScanCallback;
 import android.nearby.ScanFilter;
 import android.nearby.ScanRequest;
 import android.nearby.aidl.IOffloadCallback;
-import android.os.IBinder;
-import android.os.RemoteException;
 import android.util.Log;
 
-import com.android.internal.annotations.GuardedBy;
+import androidx.annotation.NonNull;
+
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.server.nearby.injector.Injector;
-import com.android.server.nearby.metrics.NearbyMetrics;
-import com.android.server.nearby.presence.PresenceDiscoveryResult;
+import com.android.server.nearby.managers.registration.DiscoveryRegistration;
 import com.android.server.nearby.provider.AbstractDiscoveryProvider;
 import com.android.server.nearby.provider.BleDiscoveryProvider;
 import com.android.server.nearby.provider.ChreCommunication;
 import com.android.server.nearby.provider.ChreDiscoveryProvider;
-import com.android.server.nearby.provider.PrivacyFilter;
 import com.android.server.nearby.util.identity.CallerIdentity;
-import com.android.server.nearby.util.permissions.DiscoveryPermissions;
 
 import java.util.ArrayList;
-import java.util.HashMap;
+import java.util.Collection;
 import java.util.List;
-import java.util.Map;
-import java.util.Objects;
+import java.util.Set;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
-import java.util.stream.Collectors;
+
+import javax.annotation.concurrent.GuardedBy;
 
 /** Manages all aspects of discovery providers. */
-public class DiscoveryProviderManager implements AbstractDiscoveryProvider.Listener {
+public class DiscoveryProviderManager extends
+        ListenerMultiplexer<IScanListener, DiscoveryRegistration, MergedDiscoveryRequest> implements
+        AbstractDiscoveryProvider.Listener,
+        DiscoveryManager {
 
     protected final Object mLock = new Object();
-    private final Context mContext;
-    private final BleDiscoveryProvider mBleDiscoveryProvider;
     @VisibleForTesting
     @Nullable
     final ChreDiscoveryProvider mChreDiscoveryProvider;
-    private @ScanRequest.ScanMode int mScanMode;
+    private final Context mContext;
+    private final BleDiscoveryProvider mBleDiscoveryProvider;
     private final Injector mInjector;
-
-    @GuardedBy("mLock")
-    private Map<IBinder, ScanListenerRecord> mScanTypeScanListenerRecordMap;
-
-    @Override
-    public void onNearbyDeviceDiscovered(NearbyDeviceParcelable nearbyDevice) {
-        synchronized (mLock) {
-            AppOpsManager appOpsManager = Objects.requireNonNull(mInjector.getAppOpsManager());
-            for (IBinder listenerBinder : mScanTypeScanListenerRecordMap.keySet()) {
-                ScanListenerRecord record = mScanTypeScanListenerRecordMap.get(listenerBinder);
-                if (record == null) {
-                    Log.w(TAG, "DiscoveryProviderManager cannot find the scan record.");
-                    continue;
-                }
-                CallerIdentity callerIdentity = record.getCallerIdentity();
-                if (!DiscoveryPermissions.noteDiscoveryResultDelivery(
-                        appOpsManager, callerIdentity)) {
-                    Log.w(TAG, "[DiscoveryProviderManager] scan permission revoked "
-                            + "- not forwarding results");
-                    try {
-                        record.getScanListener().onError(ScanCallback.ERROR_PERMISSION_DENIED);
-                    } catch (RemoteException e) {
-                        Log.w(TAG, "DiscoveryProviderManager failed to report error.", e);
-                    }
-                    return;
-                }
-
-                if (nearbyDevice.getScanType() == SCAN_TYPE_NEARBY_PRESENCE) {
-                    List<ScanFilter> presenceFilters =
-                            record.getScanRequest().getScanFilters().stream()
-                                    .filter(
-                                            scanFilter ->
-                                                    scanFilter.getType()
-                                                            == SCAN_TYPE_NEARBY_PRESENCE)
-                                    .collect(Collectors.toList());
-                    if (!presenceFilterMatches(nearbyDevice, presenceFilters)) {
-                        Log.d(TAG, "presence filter does not match for "
-                                + "the scanned Presence Device");
-                        continue;
-                    }
-                }
-                try {
-                    record.getScanListener()
-                            .onDiscovered(
-                                    PrivacyFilter.filter(
-                                            record.getScanRequest().getScanType(), nearbyDevice));
-                    NearbyMetrics.logScanDeviceDiscovered(
-                            record.hashCode(), record.getScanRequest(), nearbyDevice);
-                } catch (RemoteException e) {
-                    Log.w(TAG, "DiscoveryProviderManager failed to report onDiscovered.", e);
-                }
-            }
-        }
-    }
-
-    @Override
-    public void onError(int errorCode) {
-        synchronized (mLock) {
-            AppOpsManager appOpsManager = Objects.requireNonNull(mInjector.getAppOpsManager());
-            for (IBinder listenerBinder : mScanTypeScanListenerRecordMap.keySet()) {
-                ScanListenerRecord record = mScanTypeScanListenerRecordMap.get(listenerBinder);
-                if (record == null) {
-                    Log.w(TAG, "DiscoveryProviderManager cannot find the scan record.");
-                    continue;
-                }
-                CallerIdentity callerIdentity = record.getCallerIdentity();
-                if (!DiscoveryPermissions.noteDiscoveryResultDelivery(
-                        appOpsManager, callerIdentity)) {
-                    Log.w(TAG, "[DiscoveryProviderManager] scan permission revoked "
-                            + "- not forwarding results");
-                    try {
-                        record.getScanListener().onError(ScanCallback.ERROR_PERMISSION_DENIED);
-                    } catch (RemoteException e) {
-                        Log.w(TAG, "DiscoveryProviderManager failed to report error.", e);
-                    }
-                    return;
-                }
-
-                try {
-                    record.getScanListener().onError(errorCode);
-                } catch (RemoteException e) {
-                    Log.w(TAG, "DiscoveryProviderManager failed to report onError.", e);
-                }
-            }
-        }
-    }
+    private final Executor mExecutor;
 
     public DiscoveryProviderManager(Context context, Injector injector) {
+        Log.v(TAG, "DiscoveryProviderManager: ");
         mContext = context;
         mBleDiscoveryProvider = new BleDiscoveryProvider(mContext, injector);
-        Executor executor = Executors.newSingleThreadExecutor();
-        mChreDiscoveryProvider =
-                new ChreDiscoveryProvider(
-                        mContext, new ChreCommunication(injector, mContext, executor), executor);
-        mScanTypeScanListenerRecordMap = new HashMap<>();
+        mExecutor = Executors.newSingleThreadExecutor();
+        mChreDiscoveryProvider = new ChreDiscoveryProvider(mContext,
+                new ChreCommunication(injector, mContext, mExecutor), mExecutor);
         mInjector = injector;
     }
 
     @VisibleForTesting
-    DiscoveryProviderManager(Context context, Injector injector,
+    DiscoveryProviderManager(Context context, Executor executor, Injector injector,
             BleDiscoveryProvider bleDiscoveryProvider,
-            ChreDiscoveryProvider chreDiscoveryProvider,
-            Map<IBinder, ScanListenerRecord> scanTypeScanListenerRecordMap) {
+            ChreDiscoveryProvider chreDiscoveryProvider) {
         mContext = context;
+        mExecutor = executor;
         mInjector = injector;
         mBleDiscoveryProvider = bleDiscoveryProvider;
         mChreDiscoveryProvider = chreDiscoveryProvider;
-        mScanTypeScanListenerRecordMap = scanTypeScanListenerRecordMap;
     }
 
-    /** Called after boot completed. */
-    public void init() {
-        if (mInjector.getContextHubManager() != null) {
-            mChreDiscoveryProvider.init();
-        }
-        mChreDiscoveryProvider.getController().setListener(this);
-    }
-
-    /**
-     * Registers the listener in the manager and starts scan according to the requested scan mode.
-     */
-    @NearbyManager.ScanStatus
-    public int registerScanListener(ScanRequest scanRequest, IScanListener listener,
-            CallerIdentity callerIdentity) {
-        synchronized (mLock) {
-            ScanListenerDeathRecipient deathRecipient = (listener != null)
-                    ? new ScanListenerDeathRecipient(listener) : null;
-            IBinder listenerBinder = listener.asBinder();
-            if (listenerBinder != null && deathRecipient != null) {
-                try {
-                    listenerBinder.linkToDeath(deathRecipient, 0);
-                } catch (RemoteException e) {
-                    throw new IllegalArgumentException("Can't link to scan listener's death");
-                }
-            }
-            if (mScanTypeScanListenerRecordMap.containsKey(listener.asBinder())) {
-                ScanRequest savedScanRequest =
-                        mScanTypeScanListenerRecordMap.get(listenerBinder).getScanRequest();
-                if (scanRequest.equals(savedScanRequest)) {
-                    Log.d(TAG, "Already registered the scanRequest: " + scanRequest);
-                    return NearbyManager.ScanStatus.SUCCESS;
-                }
-            }
-            ScanListenerRecord scanListenerRecord =
-                    new ScanListenerRecord(scanRequest, listener, callerIdentity, deathRecipient);
-
-            Boolean started = startProviders(scanRequest);
-            if (started == null) {
-                return NearbyManager.ScanStatus.UNKNOWN;
-            }
-            if (!started) {
-                return NearbyManager.ScanStatus.ERROR;
-            }
-            mScanTypeScanListenerRecordMap.put(listenerBinder, scanListenerRecord);
-            NearbyMetrics.logScanStarted(scanListenerRecord.hashCode(), scanRequest);
-            if (mScanMode < scanRequest.getScanMode()) {
-                mScanMode = scanRequest.getScanMode();
-                invalidateProviderScanMode();
-            }
-            return NearbyManager.ScanStatus.SUCCESS;
-        }
-    }
-
-    /**
-     * Unregisters the listener in the manager and adjusts the scan mode if necessary afterwards.
-     */
-    public void unregisterScanListener(IScanListener listener) {
-        IBinder listenerBinder = listener.asBinder();
-        synchronized (mLock) {
-            if (!mScanTypeScanListenerRecordMap.containsKey(listenerBinder)) {
-                Log.w(
-                        TAG,
-                        "Cannot unregister the scanRequest because the request is never "
-                                + "registered.");
-                return;
-            }
-
-            ScanListenerRecord removedRecord =
-                    mScanTypeScanListenerRecordMap.remove(listenerBinder);
-            ScanListenerDeathRecipient deathRecipient = removedRecord.getDeathRecipient();
-            if (listenerBinder != null && deathRecipient != null) {
-                listenerBinder.unlinkToDeath(removedRecord.getDeathRecipient(), 0);
-            }
-            Log.v(TAG, "DiscoveryProviderManager unregistered scan listener.");
-            NearbyMetrics.logScanStopped(removedRecord.hashCode(), removedRecord.getScanRequest());
-            if (mScanTypeScanListenerRecordMap.isEmpty()) {
-                Log.v(TAG, "DiscoveryProviderManager stops provider because there is no "
-                        + "scan listener registered.");
-                stopProviders();
-                return;
-            }
-
-            // TODO(b/221082271): updates the scan with reduced filters.
-
-            // Removes current highest scan mode requested and sets the next highest scan mode.
-            if (removedRecord.getScanRequest().getScanMode() == mScanMode) {
-                Log.v(TAG, "DiscoveryProviderManager starts to find the new highest scan mode "
-                        + "because the highest scan mode listener was unregistered.");
-                @ScanRequest.ScanMode int highestScanModeRequested = ScanRequest.SCAN_MODE_NO_POWER;
-                // find the next highest scan mode;
-                for (ScanListenerRecord record : mScanTypeScanListenerRecordMap.values()) {
-                    @ScanRequest.ScanMode int scanMode = record.getScanRequest().getScanMode();
-                    if (scanMode > highestScanModeRequested) {
-                        highestScanModeRequested = scanMode;
-                    }
-                }
-                if (mScanMode != highestScanModeRequested) {
-                    mScanMode = highestScanModeRequested;
-                    invalidateProviderScanMode();
-                }
-            }
-        }
-    }
-
-    /**
-     * Query offload capability in a device.
-     */
-    public void queryOffloadCapability(IOffloadCallback callback) {
-        mChreDiscoveryProvider.queryOffloadCapability(callback);
-    }
-
-    /**
-     * @return {@code null} when all providers are initializing
-     * {@code false} when fail to start all the providers
-     * {@code true} when any one of the provider starts successfully
-     */
-    @VisibleForTesting
-    @Nullable
-    Boolean startProviders(ScanRequest scanRequest) {
-        if (!scanRequest.isBleEnabled()) {
-            Log.w(TAG, "failed to start any provider because client disabled BLE");
-            return false;
-        }
-        List<ScanFilter> scanFilters = getPresenceScanFilters();
-        boolean chreOnly = isChreOnly(scanFilters);
-        Boolean chreAvailable = mChreDiscoveryProvider.available();
-        if (chreAvailable == null) {
-            if (chreOnly) {
-                Log.w(TAG, "client wants CHRE only and Nearby service is still querying CHRE"
-                        + " status");
-                return null;
-            }
-            startBleProvider(scanFilters);
-            return true;
-        }
-
-        if (!chreAvailable) {
-            if (chreOnly) {
-                Log.w(TAG, "failed to start any provider because client wants CHRE only and CHRE"
-                        + " is not available");
-                return false;
-            }
-            startBleProvider(scanFilters);
-            return true;
-        }
-
-        if (scanRequest.getScanType() == SCAN_TYPE_NEARBY_PRESENCE) {
-            startChreProvider(scanFilters);
-            return true;
-        }
-
-        startBleProvider(scanFilters);
-        return true;
-    }
-
-    private static boolean isChreOnly(List<ScanFilter> scanFilters) {
+    private static boolean isChreOnly(Set<ScanFilter> scanFilters) {
         for (ScanFilter scanFilter : scanFilters) {
             List<DataElement> dataElements =
                     ((PresenceScanFilter) scanFilter).getExtendedProperties();
@@ -355,41 +109,160 @@
         return false;
     }
 
-    private void startBleProvider(List<ScanFilter> scanFilters) {
+    @Override
+    public void onNearbyDeviceDiscovered(NearbyDeviceParcelable nearbyDevice) {
+        synchronized (mMultiplexerLock) {
+            Log.d(TAG, "Found device" + nearbyDevice);
+            deliverToListeners(registration -> {
+                try {
+                    return registration.onNearbyDeviceDiscovered(nearbyDevice);
+                } catch (Exception e) {
+                    Log.w(TAG, "DiscoveryProviderManager failed to report callback.", e);
+                    return null;
+                }
+            });
+        }
+    }
+
+    @Override
+    public void onError(int errorCode) {
+        synchronized (mMultiplexerLock) {
+            Log.e(TAG, "Error found during scanning.");
+            deliverToListeners(registration -> {
+                try {
+                    return registration.reportError(errorCode);
+                } catch (Exception e) {
+                    Log.w(TAG, "DiscoveryProviderManager failed to report error.", e);
+                    return null;
+                }
+            });
+        }
+    }
+
+    /** Called after boot completed. */
+    public void init() {
+        if (mInjector.getContextHubManager() != null) {
+            mChreDiscoveryProvider.init();
+        }
+        mChreDiscoveryProvider.getController().setListener(this);
+    }
+
+    /**
+     * Registers the listener in the manager and starts scan according to the requested scan mode.
+     */
+    @NearbyManager.ScanStatus
+    public int registerScanListener(ScanRequest scanRequest, IScanListener listener,
+            CallerIdentity callerIdentity) {
+        DiscoveryRegistration registration = new DiscoveryRegistration(this, scanRequest, listener,
+                mExecutor, callerIdentity, mMultiplexerLock, mInjector.getAppOpsManager());
+        synchronized (mMultiplexerLock) {
+            putRegistration(listener.asBinder(), registration);
+            return NearbyManager.ScanStatus.SUCCESS;
+        }
+    }
+
+    @Override
+    public void onRegister() {
+        Log.v(TAG, "Registering the DiscoveryProviderManager.");
+        startProviders();
+    }
+
+    @Override
+    public void onUnregister() {
+        Log.v(TAG, "Unregistering the DiscoveryProviderManager.");
+        stopProviders();
+    }
+
+    /**
+     * Unregisters the listener in the manager and adjusts the scan mode if necessary afterwards.
+     */
+    public void unregisterScanListener(IScanListener listener) {
+        Log.v(TAG, "Unregister scan listener");
+        synchronized (mMultiplexerLock) {
+            removeRegistration(listener.asBinder());
+        }
+        // TODO(b/221082271): updates the scan with reduced filters.
+    }
+
+    /**
+     * Query offload capability in a device.
+     */
+    public void queryOffloadCapability(IOffloadCallback callback) {
+        mChreDiscoveryProvider.queryOffloadCapability(callback);
+    }
+
+    /**
+     * @return {@code null} when all providers are initializing
+     * {@code false} when fail to start all the providers
+     * {@code true} when any one of the provider starts successfully
+     */
+    @VisibleForTesting
+    @Nullable
+    Boolean startProviders() {
+        synchronized (mMultiplexerLock) {
+            if (!mMerged.getMediums().contains(MergedDiscoveryRequest.Medium.BLE)) {
+                Log.w(TAG, "failed to start any provider because client disabled BLE");
+                return false;
+            }
+            Set<ScanFilter> scanFilters = mMerged.getScanFilters();
+            boolean chreOnly = isChreOnly(scanFilters);
+            Boolean chreAvailable = mChreDiscoveryProvider.available();
+            Log.v(TAG, "startProviders: chreOnly " + chreOnly + " chreAvailable " + chreAvailable);
+            if (chreAvailable == null) {
+                if (chreOnly) {
+                    Log.w(TAG, "client wants CHRE only and Nearby service is still querying CHRE"
+                            + " status");
+                    return null;
+                }
+                startBleProvider(scanFilters);
+                return true;
+            }
+
+            if (!chreAvailable) {
+                if (chreOnly) {
+                    Log.w(TAG,
+                            "failed to start any provider because client wants CHRE only and CHRE"
+                                    + " is not available");
+                    return false;
+                }
+                startBleProvider(scanFilters);
+                return true;
+            }
+
+            if (mMerged.getScanTypes().contains(SCAN_TYPE_NEARBY_PRESENCE)) {
+                startChreProvider(scanFilters);
+                Log.d(TAG, "startProviders: heeey");
+                return true;
+            }
+
+            Log.d(TAG, "startProviders: geagewage");
+
+            startBleProvider(scanFilters);
+            return true;
+        }
+    }
+
+    @GuardedBy("mMultiplexerLock")
+    private void startBleProvider(Set<ScanFilter> scanFilters) {
         if (!mBleDiscoveryProvider.getController().isStarted()) {
             Log.d(TAG, "DiscoveryProviderManager starts Ble scanning.");
             mBleDiscoveryProvider.getController().setListener(this);
-            mBleDiscoveryProvider.getController().setProviderScanMode(mScanMode);
-            mBleDiscoveryProvider.getController().setProviderScanFilters(scanFilters);
+            mBleDiscoveryProvider.getController().setProviderScanMode(mMerged.getScanMode());
+            mBleDiscoveryProvider.getController().setProviderScanFilters(
+                    new ArrayList<>(scanFilters));
             mBleDiscoveryProvider.getController().start();
         }
     }
 
     @VisibleForTesting
-    void startChreProvider(List<ScanFilter> scanFilters) {
-        Log.d(TAG, "DiscoveryProviderManager starts CHRE scanning.");
-        mChreDiscoveryProvider.getController().setProviderScanFilters(scanFilters);
-        mChreDiscoveryProvider.getController().setProviderScanMode(mScanMode);
+    @GuardedBy("mMultiplexerLock")
+    void startChreProvider(Collection<ScanFilter> scanFilters) {
+        Log.d(TAG, "DiscoveryProviderManager starts CHRE scanning. " + mMerged);
+        mChreDiscoveryProvider.getController().setProviderScanFilters(new ArrayList<>(scanFilters));
+        mChreDiscoveryProvider.getController().setProviderScanMode(mMerged.getScanMode());
         mChreDiscoveryProvider.getController().start();
     }
 
-    private List<ScanFilter> getPresenceScanFilters() {
-        synchronized (mLock) {
-            List<ScanFilter> scanFilters = new ArrayList();
-            for (IBinder listenerBinder : mScanTypeScanListenerRecordMap.keySet()) {
-                ScanListenerRecord record = mScanTypeScanListenerRecordMap.get(listenerBinder);
-                List<ScanFilter> presenceFilters =
-                        record.getScanRequest().getScanFilters().stream()
-                                .filter(
-                                        scanFilter ->
-                                                scanFilter.getType() == SCAN_TYPE_NEARBY_PRESENCE)
-                                .collect(Collectors.toList());
-                scanFilters.addAll(presenceFilters);
-            }
-            return scanFilters;
-        }
-    }
-
     private void stopProviders() {
         stopBleProvider();
         stopChreProvider();
@@ -407,96 +280,40 @@
     @VisibleForTesting
     void invalidateProviderScanMode() {
         if (mBleDiscoveryProvider.getController().isStarted()) {
-            mBleDiscoveryProvider.getController().setProviderScanMode(mScanMode);
+            synchronized (mMultiplexerLock) {
+                mBleDiscoveryProvider.getController().setProviderScanMode(mMerged.getScanMode());
+            }
         } else {
-            Log.d(
-                    TAG,
-                    "Skip invalidating BleDiscoveryProvider scan mode because the provider not "
-                            + "started.");
+            Log.d(TAG, "Skip invalidating BleDiscoveryProvider scan mode because the provider not "
+                    + "started.");
         }
     }
 
-    @VisibleForTesting
-    static boolean presenceFilterMatches(
-            NearbyDeviceParcelable device, List<ScanFilter> scanFilters) {
-        if (scanFilters.isEmpty()) {
-            return true;
-        }
-        PresenceDiscoveryResult discoveryResult = PresenceDiscoveryResult.fromDevice(device);
-        for (ScanFilter scanFilter : scanFilters) {
-            PresenceScanFilter presenceScanFilter = (PresenceScanFilter) scanFilter;
-            if (discoveryResult.matches(presenceScanFilter)) {
-                return true;
+    @Override
+    public MergedDiscoveryRequest mergeRegistrations(
+            @NonNull Collection<DiscoveryRegistration> registrations) {
+        MergedDiscoveryRequest.Builder builder = new MergedDiscoveryRequest.Builder();
+        int scanMode = ScanRequest.SCAN_MODE_NO_POWER;
+        for (DiscoveryRegistration registration : registrations) {
+            builder.addActions(registration.getActions());
+            builder.addScanFilters(registration.getPresenceScanFilters());
+            Log.d(TAG,
+                    "mergeRegistrations: type is " + registration.getScanRequest().getScanType());
+            builder.addScanType(registration.getScanRequest().getScanType());
+            if (registration.getScanRequest().isBleEnabled()) {
+                builder.addMedium(MergedDiscoveryRequest.Medium.BLE);
+            }
+            int requestScanMode = registration.getScanRequest().getScanMode();
+            if (scanMode < requestScanMode) {
+                scanMode = requestScanMode;
             }
         }
-        return false;
+        builder.setScanMode(scanMode);
+        return builder.build();
     }
 
-    /**
-     * Class to make listener unregister after the binder is dead.
-     */
-    public class ScanListenerDeathRecipient implements IBinder.DeathRecipient {
-        public IScanListener listener;
-
-        ScanListenerDeathRecipient(IScanListener listener) {
-            this.listener = listener;
-        }
-
-        @Override
-        public void binderDied() {
-            Log.d(TAG, "Binder is dead - unregistering scan listener");
-            unregisterScanListener(listener);
-        }
-    }
-
-    @VisibleForTesting
-    static class ScanListenerRecord {
-
-        private final ScanRequest mScanRequest;
-
-        private final IScanListener mScanListener;
-
-        private final CallerIdentity mCallerIdentity;
-
-        private final ScanListenerDeathRecipient mDeathRecipient;
-
-        ScanListenerRecord(ScanRequest scanRequest, IScanListener iScanListener,
-                CallerIdentity callerIdentity, ScanListenerDeathRecipient deathRecipient) {
-            mScanListener = iScanListener;
-            mScanRequest = scanRequest;
-            mCallerIdentity = callerIdentity;
-            mDeathRecipient = deathRecipient;
-        }
-
-        IScanListener getScanListener() {
-            return mScanListener;
-        }
-
-        ScanRequest getScanRequest() {
-            return mScanRequest;
-        }
-
-        CallerIdentity getCallerIdentity() {
-            return mCallerIdentity;
-        }
-
-        ScanListenerDeathRecipient getDeathRecipient()  {
-            return mDeathRecipient;
-        }
-
-        @Override
-        public boolean equals(Object other) {
-            if (other instanceof ScanListenerRecord) {
-                ScanListenerRecord otherScanListenerRecord = (ScanListenerRecord) other;
-                return Objects.equals(mScanRequest, otherScanListenerRecord.mScanRequest)
-                        && Objects.equals(mScanListener, otherScanListenerRecord.mScanListener);
-            }
-            return false;
-        }
-
-        @Override
-        public int hashCode() {
-            return Objects.hash(mScanListener, mScanRequest);
-        }
+    @Override
+    public void onMergedRegistrationsUpdated() {
+        invalidateProviderScanMode();
     }
 }
diff --git a/nearby/service/java/com/android/server/nearby/managers/DiscoveryProviderManagerLegacy.java b/nearby/service/java/com/android/server/nearby/managers/DiscoveryProviderManagerLegacy.java
new file mode 100644
index 0000000..e68d22a
--- /dev/null
+++ b/nearby/service/java/com/android/server/nearby/managers/DiscoveryProviderManagerLegacy.java
@@ -0,0 +1,504 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.nearby.managers;
+
+import static android.nearby.ScanRequest.SCAN_TYPE_NEARBY_PRESENCE;
+
+import static com.android.server.nearby.NearbyService.TAG;
+
+import android.annotation.Nullable;
+import android.app.AppOpsManager;
+import android.content.Context;
+import android.nearby.DataElement;
+import android.nearby.IScanListener;
+import android.nearby.NearbyDeviceParcelable;
+import android.nearby.NearbyManager;
+import android.nearby.PresenceScanFilter;
+import android.nearby.ScanCallback;
+import android.nearby.ScanFilter;
+import android.nearby.ScanRequest;
+import android.nearby.aidl.IOffloadCallback;
+import android.os.IBinder;
+import android.os.RemoteException;
+import android.util.Log;
+
+import com.android.internal.annotations.GuardedBy;
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.server.nearby.injector.Injector;
+import com.android.server.nearby.metrics.NearbyMetrics;
+import com.android.server.nearby.presence.PresenceDiscoveryResult;
+import com.android.server.nearby.provider.AbstractDiscoveryProvider;
+import com.android.server.nearby.provider.BleDiscoveryProvider;
+import com.android.server.nearby.provider.ChreCommunication;
+import com.android.server.nearby.provider.ChreDiscoveryProvider;
+import com.android.server.nearby.provider.PrivacyFilter;
+import com.android.server.nearby.util.identity.CallerIdentity;
+import com.android.server.nearby.util.permissions.DiscoveryPermissions;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+import java.util.stream.Collectors;
+
+/** Manages all aspects of discovery providers. */
+public class DiscoveryProviderManagerLegacy implements AbstractDiscoveryProvider.Listener,
+        DiscoveryManager {
+
+    protected final Object mLock = new Object();
+    @VisibleForTesting
+    @Nullable
+    final ChreDiscoveryProvider mChreDiscoveryProvider;
+    private final Context mContext;
+    private final BleDiscoveryProvider mBleDiscoveryProvider;
+    private final Injector mInjector;
+    @ScanRequest.ScanMode
+    private int mScanMode;
+    @GuardedBy("mLock")
+    private final Map<IBinder, ScanListenerRecord> mScanTypeScanListenerRecordMap;
+
+    public DiscoveryProviderManagerLegacy(Context context, Injector injector) {
+        mContext = context;
+        mBleDiscoveryProvider = new BleDiscoveryProvider(mContext, injector);
+        Executor executor = Executors.newSingleThreadExecutor();
+        mChreDiscoveryProvider =
+                new ChreDiscoveryProvider(
+                        mContext, new ChreCommunication(injector, mContext, executor), executor);
+        mScanTypeScanListenerRecordMap = new HashMap<>();
+        mInjector = injector;
+        Log.v(TAG, "DiscoveryProviderManagerLegacy: ");
+    }
+
+    @VisibleForTesting
+    DiscoveryProviderManagerLegacy(Context context, Injector injector,
+            BleDiscoveryProvider bleDiscoveryProvider,
+            ChreDiscoveryProvider chreDiscoveryProvider,
+            Map<IBinder, ScanListenerRecord> scanTypeScanListenerRecordMap) {
+        mContext = context;
+        mInjector = injector;
+        mBleDiscoveryProvider = bleDiscoveryProvider;
+        mChreDiscoveryProvider = chreDiscoveryProvider;
+        mScanTypeScanListenerRecordMap = scanTypeScanListenerRecordMap;
+    }
+
+    private static boolean isChreOnly(List<ScanFilter> scanFilters) {
+        for (ScanFilter scanFilter : scanFilters) {
+            List<DataElement> dataElements =
+                    ((PresenceScanFilter) scanFilter).getExtendedProperties();
+            for (DataElement dataElement : dataElements) {
+                if (dataElement.getKey() != DataElement.DataType.SCAN_MODE) {
+                    continue;
+                }
+                byte[] scanModeValue = dataElement.getValue();
+                if (scanModeValue == null || scanModeValue.length == 0) {
+                    break;
+                }
+                if (Byte.toUnsignedInt(scanModeValue[0]) == ScanRequest.SCAN_MODE_CHRE_ONLY) {
+                    return true;
+                }
+            }
+
+        }
+        return false;
+    }
+
+    @VisibleForTesting
+    static boolean presenceFilterMatches(
+            NearbyDeviceParcelable device, List<ScanFilter> scanFilters) {
+        if (scanFilters.isEmpty()) {
+            return true;
+        }
+        PresenceDiscoveryResult discoveryResult = PresenceDiscoveryResult.fromDevice(device);
+        for (ScanFilter scanFilter : scanFilters) {
+            PresenceScanFilter presenceScanFilter = (PresenceScanFilter) scanFilter;
+            if (discoveryResult.matches(presenceScanFilter)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    @Override
+    public void onNearbyDeviceDiscovered(NearbyDeviceParcelable nearbyDevice) {
+        synchronized (mLock) {
+            AppOpsManager appOpsManager = Objects.requireNonNull(mInjector.getAppOpsManager());
+            for (IBinder listenerBinder : mScanTypeScanListenerRecordMap.keySet()) {
+                ScanListenerRecord record = mScanTypeScanListenerRecordMap.get(listenerBinder);
+                if (record == null) {
+                    Log.w(TAG, "DiscoveryProviderManager cannot find the scan record.");
+                    continue;
+                }
+                CallerIdentity callerIdentity = record.getCallerIdentity();
+                if (!DiscoveryPermissions.noteDiscoveryResultDelivery(
+                        appOpsManager, callerIdentity)) {
+                    Log.w(TAG, "[DiscoveryProviderManager] scan permission revoked "
+                            + "- not forwarding results");
+                    try {
+                        record.getScanListener().onError(ScanCallback.ERROR_PERMISSION_DENIED);
+                    } catch (RemoteException e) {
+                        Log.w(TAG, "DiscoveryProviderManager failed to report error.", e);
+                    }
+                    return;
+                }
+
+                if (nearbyDevice.getScanType() == SCAN_TYPE_NEARBY_PRESENCE) {
+                    List<ScanFilter> presenceFilters =
+                            record.getScanRequest().getScanFilters().stream()
+                                    .filter(
+                                            scanFilter ->
+                                                    scanFilter.getType()
+                                                            == SCAN_TYPE_NEARBY_PRESENCE)
+                                    .collect(Collectors.toList());
+                    if (!presenceFilterMatches(nearbyDevice, presenceFilters)) {
+                        Log.d(TAG, "presence filter does not match for "
+                                + "the scanned Presence Device");
+                        continue;
+                    }
+                }
+                try {
+                    record.getScanListener()
+                            .onDiscovered(
+                                    PrivacyFilter.filter(
+                                            record.getScanRequest().getScanType(), nearbyDevice));
+                    NearbyMetrics.logScanDeviceDiscovered(
+                            record.hashCode(), record.getScanRequest(), nearbyDevice);
+                } catch (RemoteException e) {
+                    Log.w(TAG, "DiscoveryProviderManager failed to report onDiscovered.", e);
+                }
+            }
+        }
+    }
+
+    @Override
+    public void onError(int errorCode) {
+        synchronized (mLock) {
+            AppOpsManager appOpsManager = Objects.requireNonNull(mInjector.getAppOpsManager());
+            for (IBinder listenerBinder : mScanTypeScanListenerRecordMap.keySet()) {
+                ScanListenerRecord record = mScanTypeScanListenerRecordMap.get(listenerBinder);
+                if (record == null) {
+                    Log.w(TAG, "DiscoveryProviderManager cannot find the scan record.");
+                    continue;
+                }
+                CallerIdentity callerIdentity = record.getCallerIdentity();
+                if (!DiscoveryPermissions.noteDiscoveryResultDelivery(
+                        appOpsManager, callerIdentity)) {
+                    Log.w(TAG, "[DiscoveryProviderManager] scan permission revoked "
+                            + "- not forwarding results");
+                    try {
+                        record.getScanListener().onError(ScanCallback.ERROR_PERMISSION_DENIED);
+                    } catch (RemoteException e) {
+                        Log.w(TAG, "DiscoveryProviderManager failed to report error.", e);
+                    }
+                    return;
+                }
+
+                try {
+                    record.getScanListener().onError(errorCode);
+                } catch (RemoteException e) {
+                    Log.w(TAG, "DiscoveryProviderManager failed to report onError.", e);
+                }
+            }
+        }
+    }
+
+    /** Called after boot completed. */
+    public void init() {
+        if (mInjector.getContextHubManager() != null) {
+            mChreDiscoveryProvider.init();
+        }
+        mChreDiscoveryProvider.getController().setListener(this);
+    }
+
+    /**
+     * Registers the listener in the manager and starts scan according to the requested scan mode.
+     */
+    @NearbyManager.ScanStatus
+    public int registerScanListener(ScanRequest scanRequest, IScanListener listener,
+            CallerIdentity callerIdentity) {
+        synchronized (mLock) {
+            ScanListenerDeathRecipient deathRecipient = (listener != null)
+                    ? new ScanListenerDeathRecipient(listener) : null;
+            IBinder listenerBinder = listener.asBinder();
+            if (listenerBinder != null && deathRecipient != null) {
+                try {
+                    listenerBinder.linkToDeath(deathRecipient, 0);
+                } catch (RemoteException e) {
+                    throw new IllegalArgumentException("Can't link to scan listener's death");
+                }
+            }
+            if (mScanTypeScanListenerRecordMap.containsKey(listener.asBinder())) {
+                ScanRequest savedScanRequest =
+                        mScanTypeScanListenerRecordMap.get(listenerBinder).getScanRequest();
+                if (scanRequest.equals(savedScanRequest)) {
+                    Log.d(TAG, "Already registered the scanRequest: " + scanRequest);
+                    return NearbyManager.ScanStatus.SUCCESS;
+                }
+            }
+            ScanListenerRecord scanListenerRecord =
+                    new ScanListenerRecord(scanRequest, listener, callerIdentity, deathRecipient);
+
+            Boolean started = startProviders(scanRequest);
+            if (started == null) {
+                return NearbyManager.ScanStatus.UNKNOWN;
+            }
+            if (!started) {
+                return NearbyManager.ScanStatus.ERROR;
+            }
+            mScanTypeScanListenerRecordMap.put(listenerBinder, scanListenerRecord);
+            NearbyMetrics.logScanStarted(scanListenerRecord.hashCode(), scanRequest);
+            if (mScanMode < scanRequest.getScanMode()) {
+                mScanMode = scanRequest.getScanMode();
+                invalidateProviderScanMode();
+            }
+            return NearbyManager.ScanStatus.SUCCESS;
+        }
+    }
+
+    /**
+     * Unregisters the listener in the manager and adjusts the scan mode if necessary afterwards.
+     */
+    public void unregisterScanListener(IScanListener listener) {
+        IBinder listenerBinder = listener.asBinder();
+        synchronized (mLock) {
+            if (!mScanTypeScanListenerRecordMap.containsKey(listenerBinder)) {
+                Log.w(
+                        TAG,
+                        "Cannot unregister the scanRequest because the request is never "
+                                + "registered.");
+                return;
+            }
+
+            ScanListenerRecord removedRecord =
+                    mScanTypeScanListenerRecordMap.remove(listenerBinder);
+            ScanListenerDeathRecipient deathRecipient = removedRecord.getDeathRecipient();
+            if (listenerBinder != null && deathRecipient != null) {
+                listenerBinder.unlinkToDeath(removedRecord.getDeathRecipient(), 0);
+            }
+            Log.v(TAG, "DiscoveryProviderManager unregistered scan listener.");
+            NearbyMetrics.logScanStopped(removedRecord.hashCode(), removedRecord.getScanRequest());
+            if (mScanTypeScanListenerRecordMap.isEmpty()) {
+                Log.v(TAG, "DiscoveryProviderManager stops provider because there is no "
+                        + "scan listener registered.");
+                stopProviders();
+                return;
+            }
+
+            // TODO(b/221082271): updates the scan with reduced filters.
+
+            // Removes current highest scan mode requested and sets the next highest scan mode.
+            if (removedRecord.getScanRequest().getScanMode() == mScanMode) {
+                Log.v(TAG, "DiscoveryProviderManager starts to find the new highest scan mode "
+                        + "because the highest scan mode listener was unregistered.");
+                @ScanRequest.ScanMode int highestScanModeRequested = ScanRequest.SCAN_MODE_NO_POWER;
+                // find the next highest scan mode;
+                for (ScanListenerRecord record : mScanTypeScanListenerRecordMap.values()) {
+                    @ScanRequest.ScanMode int scanMode = record.getScanRequest().getScanMode();
+                    if (scanMode > highestScanModeRequested) {
+                        highestScanModeRequested = scanMode;
+                    }
+                }
+                if (mScanMode != highestScanModeRequested) {
+                    mScanMode = highestScanModeRequested;
+                    invalidateProviderScanMode();
+                }
+            }
+        }
+    }
+
+    /**
+     * Query offload capability in a device.
+     */
+    public void queryOffloadCapability(IOffloadCallback callback) {
+        mChreDiscoveryProvider.queryOffloadCapability(callback);
+    }
+
+    /**
+     * @return {@code null} when all providers are initializing
+     * {@code false} when fail to start all the providers
+     * {@code true} when any one of the provider starts successfully
+     */
+    @VisibleForTesting
+    @Nullable
+    Boolean startProviders(ScanRequest scanRequest) {
+        if (!scanRequest.isBleEnabled()) {
+            Log.w(TAG, "failed to start any provider because client disabled BLE");
+            return false;
+        }
+        List<ScanFilter> scanFilters = getPresenceScanFilters();
+        boolean chreOnly = isChreOnly(scanFilters);
+        Boolean chreAvailable = mChreDiscoveryProvider.available();
+        if (chreAvailable == null) {
+            if (chreOnly) {
+                Log.w(TAG, "client wants CHRE only and Nearby service is still querying CHRE"
+                        + " status");
+                return null;
+            }
+            startBleProvider(scanFilters);
+            return true;
+        }
+
+        if (!chreAvailable) {
+            if (chreOnly) {
+                Log.w(TAG, "failed to start any provider because client wants CHRE only and CHRE"
+                        + " is not available");
+                return false;
+            }
+            startBleProvider(scanFilters);
+            return true;
+        }
+
+        if (scanRequest.getScanType() == SCAN_TYPE_NEARBY_PRESENCE) {
+            startChreProvider(scanFilters);
+            return true;
+        }
+
+        startBleProvider(scanFilters);
+        return true;
+    }
+
+    private void startBleProvider(List<ScanFilter> scanFilters) {
+        if (!mBleDiscoveryProvider.getController().isStarted()) {
+            Log.d(TAG, "DiscoveryProviderManager starts Ble scanning.");
+            mBleDiscoveryProvider.getController().setListener(this);
+            mBleDiscoveryProvider.getController().setProviderScanMode(mScanMode);
+            mBleDiscoveryProvider.getController().setProviderScanFilters(scanFilters);
+            mBleDiscoveryProvider.getController().start();
+        }
+    }
+
+    @VisibleForTesting
+    void startChreProvider(List<ScanFilter> scanFilters) {
+        Log.d(TAG, "DiscoveryProviderManager starts CHRE scanning.");
+        mChreDiscoveryProvider.getController().setProviderScanFilters(scanFilters);
+        mChreDiscoveryProvider.getController().setProviderScanMode(mScanMode);
+        mChreDiscoveryProvider.getController().start();
+    }
+
+    private List<ScanFilter> getPresenceScanFilters() {
+        synchronized (mLock) {
+            List<ScanFilter> scanFilters = new ArrayList();
+            for (IBinder listenerBinder : mScanTypeScanListenerRecordMap.keySet()) {
+                ScanListenerRecord record = mScanTypeScanListenerRecordMap.get(listenerBinder);
+                List<ScanFilter> presenceFilters =
+                        record.getScanRequest().getScanFilters().stream()
+                                .filter(
+                                        scanFilter ->
+                                                scanFilter.getType() == SCAN_TYPE_NEARBY_PRESENCE)
+                                .collect(Collectors.toList());
+                scanFilters.addAll(presenceFilters);
+            }
+            return scanFilters;
+        }
+    }
+
+    private void stopProviders() {
+        stopBleProvider();
+        stopChreProvider();
+    }
+
+    private void stopBleProvider() {
+        mBleDiscoveryProvider.getController().stop();
+    }
+
+    @VisibleForTesting
+    protected void stopChreProvider() {
+        mChreDiscoveryProvider.getController().stop();
+    }
+
+    @VisibleForTesting
+    void invalidateProviderScanMode() {
+        if (mBleDiscoveryProvider.getController().isStarted()) {
+            mBleDiscoveryProvider.getController().setProviderScanMode(mScanMode);
+        } else {
+            Log.d(
+                    TAG,
+                    "Skip invalidating BleDiscoveryProvider scan mode because the provider not "
+                            + "started.");
+        }
+    }
+
+    @VisibleForTesting
+    static class ScanListenerRecord {
+
+        private final ScanRequest mScanRequest;
+
+        private final IScanListener mScanListener;
+
+        private final CallerIdentity mCallerIdentity;
+
+        private final ScanListenerDeathRecipient mDeathRecipient;
+
+        ScanListenerRecord(ScanRequest scanRequest, IScanListener iScanListener,
+                CallerIdentity callerIdentity, ScanListenerDeathRecipient deathRecipient) {
+            mScanListener = iScanListener;
+            mScanRequest = scanRequest;
+            mCallerIdentity = callerIdentity;
+            mDeathRecipient = deathRecipient;
+        }
+
+        IScanListener getScanListener() {
+            return mScanListener;
+        }
+
+        ScanRequest getScanRequest() {
+            return mScanRequest;
+        }
+
+        CallerIdentity getCallerIdentity() {
+            return mCallerIdentity;
+        }
+
+        ScanListenerDeathRecipient getDeathRecipient() {
+            return mDeathRecipient;
+        }
+
+        @Override
+        public boolean equals(Object other) {
+            if (other instanceof ScanListenerRecord) {
+                ScanListenerRecord otherScanListenerRecord = (ScanListenerRecord) other;
+                return Objects.equals(mScanRequest, otherScanListenerRecord.mScanRequest)
+                        && Objects.equals(mScanListener, otherScanListenerRecord.mScanListener);
+            }
+            return false;
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(mScanListener, mScanRequest);
+        }
+    }
+
+    /**
+     * Class to make listener unregister after the binder is dead.
+     */
+    public class ScanListenerDeathRecipient implements IBinder.DeathRecipient {
+        public IScanListener listener;
+
+        ScanListenerDeathRecipient(IScanListener listener) {
+            this.listener = listener;
+        }
+
+        @Override
+        public void binderDied() {
+            Log.d(TAG, "Binder is dead - unregistering scan listener");
+            unregisterScanListener(listener);
+        }
+    }
+}
diff --git a/nearby/service/java/com/android/server/nearby/managers/registration/DiscoveryRegistration.java b/nearby/service/java/com/android/server/nearby/managers/registration/DiscoveryRegistration.java
index 1cb70ac..bef319ec 100644
--- a/nearby/service/java/com/android/server/nearby/managers/registration/DiscoveryRegistration.java
+++ b/nearby/service/java/com/android/server/nearby/managers/registration/DiscoveryRegistration.java
@@ -243,6 +243,11 @@
 
     }
 
+    /** Reports an error to the client. */
+    public ListenerOperation<IScanListener> reportError(@ScanCallback.ErrorCode int errorCode) {
+        return listener -> listener.onError(errorCode);
+    }
+
     @Nullable
     ListenerOperation<IScanListener> reportResult(@DiscoveryResult int result,
             NearbyDeviceParcelable device, @Nullable Runnable successReportCallback) {
@@ -250,7 +255,7 @@
         // NOTE: AppOps report has to be the last operation before delivering the result. Otherwise
         // we may over-report when the discovery result doesn't end up being delivered.
         if (!checkIdentity()) {
-            return listener -> listener.onError(ScanCallback.ERROR_PERMISSION_DENIED);
+            return reportError(ScanCallback.ERROR_PERMISSION_DENIED);
         }
 
         return new ListenerOperation<>() {
diff --git a/nearby/tests/unit/src/com/android/server/nearby/NearbyServiceTest.java b/nearby/tests/unit/src/com/android/server/nearby/NearbyServiceTest.java
index 0d46d3e..90c85ab 100644
--- a/nearby/tests/unit/src/com/android/server/nearby/NearbyServiceTest.java
+++ b/nearby/tests/unit/src/com/android/server/nearby/NearbyServiceTest.java
@@ -36,6 +36,7 @@
 import android.content.Context;
 import android.nearby.IScanListener;
 import android.nearby.ScanRequest;
+import android.os.IBinder;
 import android.provider.DeviceConfig;
 
 import androidx.test.platform.app.InstrumentationRegistry;
@@ -61,10 +62,14 @@
     private IScanListener mScanListener;
     @Mock
     private AppOpsManager mMockAppOpsManager;
+    @Mock
+    private IBinder mIBinder;
 
     @Before
     public void setUp()  {
         initMocks(this);
+        when(mScanListener.asBinder()).thenReturn(mIBinder);
+
         mUiAutomation.adoptShellPermissionIdentity(
                 READ_DEVICE_CONFIG, WRITE_DEVICE_CONFIG, BLUETOOTH_PRIVILEGED);
         mContext = InstrumentationRegistry.getInstrumentation().getContext();
diff --git a/nearby/tests/unit/src/com/android/server/nearby/managers/DiscoveryProviderManagerLegacyTest.java b/nearby/tests/unit/src/com/android/server/nearby/managers/DiscoveryProviderManagerLegacyTest.java
new file mode 100644
index 0000000..aa0dad3
--- /dev/null
+++ b/nearby/tests/unit/src/com/android/server/nearby/managers/DiscoveryProviderManagerLegacyTest.java
@@ -0,0 +1,378 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.nearby.managers;
+
+import static android.nearby.PresenceCredential.IDENTITY_TYPE_PRIVATE;
+import static android.nearby.ScanRequest.SCAN_TYPE_NEARBY_PRESENCE;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.atLeastOnce;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.app.AppOpsManager;
+import android.content.Context;
+import android.nearby.DataElement;
+import android.nearby.IScanListener;
+import android.nearby.NearbyDeviceParcelable;
+import android.nearby.PresenceScanFilter;
+import android.nearby.PublicCredential;
+import android.nearby.ScanRequest;
+import android.os.IBinder;
+
+import com.android.server.nearby.injector.Injector;
+import com.android.server.nearby.provider.BleDiscoveryProvider;
+import com.android.server.nearby.provider.ChreCommunication;
+import com.android.server.nearby.provider.ChreDiscoveryProvider;
+import com.android.server.nearby.provider.DiscoveryProviderController;
+import com.android.server.nearby.util.identity.CallerIdentity;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+/**
+ * Unit test for {@link DiscoveryProviderManagerLegacy} class.
+ */
+public class DiscoveryProviderManagerLegacyTest {
+    private static final int SCAN_MODE_CHRE_ONLY = 3;
+    private static final int DATA_TYPE_SCAN_MODE = 102;
+    private static final int UID = 1234;
+    private static final int PID = 5678;
+    private static final String PACKAGE_NAME = "android.nearby.test";
+    private static final int RSSI = -60;
+    @Mock
+    Injector mInjector;
+    @Mock
+    Context mContext;
+    @Mock
+    AppOpsManager mAppOpsManager;
+    @Mock
+    BleDiscoveryProvider mBleDiscoveryProvider;
+    @Mock
+    ChreDiscoveryProvider mChreDiscoveryProvider;
+    @Mock
+    DiscoveryProviderController mBluetoothController;
+    @Mock
+    DiscoveryProviderController mChreController;
+    @Mock
+    IScanListener mScanListener;
+    @Mock
+    CallerIdentity mCallerIdentity;
+    @Mock
+    DiscoveryProviderManagerLegacy.ScanListenerDeathRecipient mScanListenerDeathRecipient;
+    @Mock
+    IBinder mIBinder;
+    private DiscoveryProviderManagerLegacy mDiscoveryProviderManager;
+    private Map<IBinder, DiscoveryProviderManagerLegacy.ScanListenerRecord>
+            mScanTypeScanListenerRecordMap;
+
+    private static PresenceScanFilter getPresenceScanFilter() {
+        final byte[] secretId = new byte[]{1, 2, 3, 4};
+        final byte[] authenticityKey = new byte[]{0, 1, 1, 1};
+        final byte[] publicKey = new byte[]{1, 1, 2, 2};
+        final byte[] encryptedMetadata = new byte[]{1, 2, 3, 4, 5};
+        final byte[] metadataEncryptionKeyTag = new byte[]{1, 1, 3, 4, 5};
+
+        PublicCredential credential = new PublicCredential.Builder(
+                secretId, authenticityKey, publicKey, encryptedMetadata, metadataEncryptionKeyTag)
+                .setIdentityType(IDENTITY_TYPE_PRIVATE)
+                .build();
+
+        final int action = 123;
+        return new PresenceScanFilter.Builder()
+                .addCredential(credential)
+                .setMaxPathLoss(RSSI)
+                .addPresenceAction(action)
+                .build();
+    }
+
+    private static PresenceScanFilter getChreOnlyPresenceScanFilter() {
+        final byte[] secretId = new byte[]{1, 2, 3, 4};
+        final byte[] authenticityKey = new byte[]{0, 1, 1, 1};
+        final byte[] publicKey = new byte[]{1, 1, 2, 2};
+        final byte[] encryptedMetadata = new byte[]{1, 2, 3, 4, 5};
+        final byte[] metadataEncryptionKeyTag = new byte[]{1, 1, 3, 4, 5};
+
+        PublicCredential credential = new PublicCredential.Builder(
+                secretId, authenticityKey, publicKey, encryptedMetadata, metadataEncryptionKeyTag)
+                .setIdentityType(IDENTITY_TYPE_PRIVATE)
+                .build();
+
+        final int action = 123;
+        DataElement scanModeElement = new DataElement(DATA_TYPE_SCAN_MODE,
+                new byte[]{SCAN_MODE_CHRE_ONLY});
+        return new PresenceScanFilter.Builder()
+                .addCredential(credential)
+                .setMaxPathLoss(RSSI)
+                .addPresenceAction(action)
+                .addExtendedProperty(scanModeElement)
+                .build();
+    }
+
+    @Before
+    public void setup() {
+        MockitoAnnotations.initMocks(this);
+        when(mInjector.getAppOpsManager()).thenReturn(mAppOpsManager);
+        when(mBleDiscoveryProvider.getController()).thenReturn(mBluetoothController);
+        when(mChreDiscoveryProvider.getController()).thenReturn(mChreController);
+
+        mScanTypeScanListenerRecordMap = new HashMap<>();
+        mDiscoveryProviderManager =
+                new DiscoveryProviderManagerLegacy(mContext, mInjector,
+                        mBleDiscoveryProvider,
+                        mChreDiscoveryProvider,
+                        mScanTypeScanListenerRecordMap);
+        mCallerIdentity = CallerIdentity
+                .forTest(UID, PID, PACKAGE_NAME, /* attributionTag= */ null);
+    }
+
+    @Test
+    public void testOnNearbyDeviceDiscovered() {
+        NearbyDeviceParcelable nearbyDeviceParcelable = new NearbyDeviceParcelable.Builder()
+                .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
+                .build();
+        mDiscoveryProviderManager.onNearbyDeviceDiscovered(nearbyDeviceParcelable);
+    }
+
+    @Test
+    public void testInvalidateProviderScanMode() {
+        mDiscoveryProviderManager.invalidateProviderScanMode();
+    }
+
+    @Test
+    public void testStartProviders_chreOnlyChreAvailable_bleProviderNotStarted() {
+        when(mChreDiscoveryProvider.available()).thenReturn(true);
+
+        ScanRequest scanRequest = new ScanRequest.Builder()
+                .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
+                .addScanFilter(getChreOnlyPresenceScanFilter()).build();
+        DiscoveryProviderManagerLegacy.ScanListenerRecord record =
+                new DiscoveryProviderManagerLegacy.ScanListenerRecord(
+                        scanRequest, mScanListener,
+                        mCallerIdentity, mScanListenerDeathRecipient);
+        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+
+        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        verify(mBluetoothController, never()).start();
+        assertThat(start).isTrue();
+    }
+
+    @Test
+    public void testStartProviders_chreOnlyChreAvailable_multipleFilters_bleProviderNotStarted() {
+        when(mChreDiscoveryProvider.available()).thenReturn(true);
+
+        ScanRequest scanRequest = new ScanRequest.Builder()
+                .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
+                .addScanFilter(getChreOnlyPresenceScanFilter())
+                .addScanFilter(getPresenceScanFilter()).build();
+        DiscoveryProviderManagerLegacy.ScanListenerRecord record =
+                new DiscoveryProviderManagerLegacy.ScanListenerRecord(
+                        scanRequest, mScanListener,
+                        mCallerIdentity, mScanListenerDeathRecipient);
+        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+
+        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        verify(mBluetoothController, never()).start();
+        assertThat(start).isTrue();
+    }
+
+    @Test
+    public void testStartProviders_chreOnlyChreUnavailable_bleProviderNotStarted() {
+        when(mChreDiscoveryProvider.available()).thenReturn(false);
+
+        ScanRequest scanRequest = new ScanRequest.Builder()
+                .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
+                .addScanFilter(getChreOnlyPresenceScanFilter()).build();
+        DiscoveryProviderManagerLegacy.ScanListenerRecord record =
+                new DiscoveryProviderManagerLegacy.ScanListenerRecord(
+                        scanRequest, mScanListener,
+                        mCallerIdentity, mScanListenerDeathRecipient);
+        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+
+        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        verify(mBluetoothController, never()).start();
+        assertThat(start).isFalse();
+    }
+
+    @Test
+    public void testStartProviders_notChreOnlyChreAvailable_bleProviderNotStarted() {
+        when(mChreDiscoveryProvider.available()).thenReturn(true);
+
+        ScanRequest scanRequest = new ScanRequest.Builder()
+                .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
+                .addScanFilter(getPresenceScanFilter()).build();
+        DiscoveryProviderManagerLegacy.ScanListenerRecord record =
+                new DiscoveryProviderManagerLegacy.ScanListenerRecord(
+                        scanRequest, mScanListener,
+                        mCallerIdentity, mScanListenerDeathRecipient);
+        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+
+        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        verify(mBluetoothController, never()).start();
+        assertThat(start).isTrue();
+    }
+
+    @Test
+    public void testStartProviders_notChreOnlyChreUnavailable_bleProviderStarted() {
+        when(mChreDiscoveryProvider.available()).thenReturn(false);
+
+        ScanRequest scanRequest = new ScanRequest.Builder()
+                .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
+                .addScanFilter(getPresenceScanFilter()).build();
+        DiscoveryProviderManagerLegacy.ScanListenerRecord record =
+                new DiscoveryProviderManagerLegacy.ScanListenerRecord(
+                        scanRequest, mScanListener,
+                        mCallerIdentity, mScanListenerDeathRecipient);
+        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+
+        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        verify(mBluetoothController, atLeastOnce()).start();
+        assertThat(start).isTrue();
+    }
+
+    @Test
+    public void testStartProviders_chreOnlyChreUndetermined_bleProviderNotStarted() {
+        when(mChreDiscoveryProvider.available()).thenReturn(null);
+
+        ScanRequest scanRequest = new ScanRequest.Builder()
+                .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
+                .addScanFilter(getChreOnlyPresenceScanFilter()).build();
+        DiscoveryProviderManagerLegacy.ScanListenerRecord record =
+                new DiscoveryProviderManagerLegacy.ScanListenerRecord(
+                        scanRequest, mScanListener,
+                        mCallerIdentity, mScanListenerDeathRecipient);
+        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+
+        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        verify(mBluetoothController, never()).start();
+        assertThat(start).isNull();
+    }
+
+    @Test
+    public void testStartProviders_notChreOnlyChreUndetermined_bleProviderStarted() {
+        when(mChreDiscoveryProvider.available()).thenReturn(null);
+
+        ScanRequest scanRequest = new ScanRequest.Builder()
+                .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
+                .addScanFilter(getPresenceScanFilter()).build();
+        DiscoveryProviderManagerLegacy.ScanListenerRecord record =
+                new DiscoveryProviderManagerLegacy.ScanListenerRecord(
+                        scanRequest, mScanListener,
+                        mCallerIdentity, mScanListenerDeathRecipient);
+        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+
+        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        verify(mBluetoothController, atLeastOnce()).start();
+        assertThat(start).isTrue();
+    }
+
+    @Test
+    public void test_stopChreProvider_clearFilters() throws Exception {
+        // Cannot use mocked ChreDiscoveryProvider,
+        // so we cannot use class variable mDiscoveryProviderManager
+        ExecutorService executor = Executors.newSingleThreadExecutor();
+        DiscoveryProviderManagerLegacy manager =
+                new DiscoveryProviderManagerLegacy(mContext, mInjector,
+                        mBleDiscoveryProvider,
+                        new ChreDiscoveryProvider(
+                                mContext,
+                                new ChreCommunication(mInjector, mContext, executor), executor),
+                        mScanTypeScanListenerRecordMap);
+        ScanRequest scanRequest = new ScanRequest.Builder()
+                .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
+                .addScanFilter(getPresenceScanFilter()).build();
+        DiscoveryProviderManagerLegacy.ScanListenerRecord record =
+                new DiscoveryProviderManagerLegacy.ScanListenerRecord(
+                        scanRequest, mScanListener,
+                        mCallerIdentity, mScanListenerDeathRecipient);
+        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+        manager.startChreProvider(List.of(getPresenceScanFilter()));
+        // This is an asynchronized process. The filters will be set in executor thread. So we need
+        // to wait for some time to get the correct result.
+        Thread.sleep(200);
+
+        assertThat(manager.mChreDiscoveryProvider.getController().isStarted())
+                .isTrue();
+        assertThat(manager.mChreDiscoveryProvider.getFiltersLocked()).isNotNull();
+
+        manager.stopChreProvider();
+        Thread.sleep(200);
+        // The filters should be cleared right after.
+        assertThat(manager.mChreDiscoveryProvider.getController().isStarted())
+                .isFalse();
+        assertThat(manager.mChreDiscoveryProvider.getFiltersLocked()).isEmpty();
+    }
+
+    @Test
+    public void test_restartChreProvider() throws Exception {
+        // Cannot use mocked ChreDiscoveryProvider,
+        // so we cannot use class variable mDiscoveryProviderManager
+        ExecutorService executor = Executors.newSingleThreadExecutor();
+        DiscoveryProviderManagerLegacy manager =
+                new DiscoveryProviderManagerLegacy(mContext, mInjector,
+                        mBleDiscoveryProvider,
+                        new ChreDiscoveryProvider(
+                                mContext,
+                                new ChreCommunication(mInjector, mContext, executor), executor),
+                        mScanTypeScanListenerRecordMap);
+        ScanRequest scanRequest = new ScanRequest.Builder()
+                .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
+                .addScanFilter(getPresenceScanFilter()).build();
+        DiscoveryProviderManagerLegacy.ScanListenerRecord record =
+                new DiscoveryProviderManagerLegacy.ScanListenerRecord(scanRequest, mScanListener,
+                        mCallerIdentity, mScanListenerDeathRecipient);
+        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+        manager.startChreProvider(List.of(getPresenceScanFilter()));
+        // This is an asynchronized process. The filters will be set in executor thread. So we need
+        // to wait for some time to get the correct result.
+        Thread.sleep(200);
+
+        assertThat(manager.mChreDiscoveryProvider.getController().isStarted())
+                .isTrue();
+        assertThat(manager.mChreDiscoveryProvider.getFiltersLocked()).isNotNull();
+
+        // We want to make sure quickly restart the provider the filters should
+        // be reset correctly.
+        // See b/255922206, there can be a race condition that filters get cleared because onStop()
+        // get executed after onStart() if they are called from different threads.
+        manager.stopChreProvider();
+        manager.mChreDiscoveryProvider.getController().setProviderScanFilters(
+                List.of(getPresenceScanFilter()));
+        manager.startChreProvider(List.of(getPresenceScanFilter()));
+        Thread.sleep(200);
+        assertThat(manager.mChreDiscoveryProvider.getController().isStarted())
+                .isTrue();
+        assertThat(manager.mChreDiscoveryProvider.getFiltersLocked()).isNotNull();
+
+        // Wait for enough time
+        Thread.sleep(1000);
+
+        assertThat(manager.mChreDiscoveryProvider.getController().isStarted())
+                .isTrue();
+        assertThat(manager.mChreDiscoveryProvider.getFiltersLocked()).isNotNull();
+    }
+}
diff --git a/nearby/tests/unit/src/com/android/server/nearby/managers/DiscoveryProviderManagerTest.java b/nearby/tests/unit/src/com/android/server/nearby/managers/DiscoveryProviderManagerTest.java
index 542ceed..7ecf631 100644
--- a/nearby/tests/unit/src/com/android/server/nearby/managers/DiscoveryProviderManagerTest.java
+++ b/nearby/tests/unit/src/com/android/server/nearby/managers/DiscoveryProviderManagerTest.java
@@ -23,6 +23,7 @@
 
 import static org.mockito.Mockito.atLeastOnce;
 import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.reset;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
@@ -48,10 +49,8 @@
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
-import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
 
 public class DiscoveryProviderManagerTest {
@@ -80,12 +79,9 @@
     @Mock
     CallerIdentity mCallerIdentity;
     @Mock
-    DiscoveryProviderManager.ScanListenerDeathRecipient mScanListenerDeathRecipient;
-    @Mock
     IBinder mIBinder;
+    private Executor mExecutor;
     private DiscoveryProviderManager mDiscoveryProviderManager;
-    private Map<IBinder, DiscoveryProviderManager.ScanListenerRecord>
-            mScanTypeScanListenerRecordMap;
 
     private static PresenceScanFilter getPresenceScanFilter() {
         final byte[] secretId = new byte[]{1, 2, 3, 4};
@@ -133,16 +129,16 @@
     @Before
     public void setup() {
         MockitoAnnotations.initMocks(this);
+        mExecutor = Executors.newSingleThreadExecutor();
         when(mInjector.getAppOpsManager()).thenReturn(mAppOpsManager);
         when(mBleDiscoveryProvider.getController()).thenReturn(mBluetoothController);
         when(mChreDiscoveryProvider.getController()).thenReturn(mChreController);
+        when(mScanListener.asBinder()).thenReturn(mIBinder);
 
-        mScanTypeScanListenerRecordMap = new HashMap<>();
         mDiscoveryProviderManager =
-                new DiscoveryProviderManager(mContext, mInjector,
+                new DiscoveryProviderManager(mContext, mExecutor, mInjector,
                         mBleDiscoveryProvider,
-                        mChreDiscoveryProvider,
-                        mScanTypeScanListenerRecordMap);
+                        mChreDiscoveryProvider);
         mCallerIdentity = CallerIdentity
                 .forTest(UID, PID, PACKAGE_NAME, /* attributionTag= */ null);
     }
@@ -162,55 +158,45 @@
 
     @Test
     public void testStartProviders_chreOnlyChreAvailable_bleProviderNotStarted() {
+        reset(mBluetoothController);
         when(mChreDiscoveryProvider.available()).thenReturn(true);
 
         ScanRequest scanRequest = new ScanRequest.Builder()
                 .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
                 .addScanFilter(getChreOnlyPresenceScanFilter()).build();
-        DiscoveryProviderManager.ScanListenerRecord record =
-                new DiscoveryProviderManager.ScanListenerRecord(
-                        scanRequest, mScanListener,
-                        mCallerIdentity, mScanListenerDeathRecipient);
-        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+        mDiscoveryProviderManager.registerScanListener(scanRequest, mScanListener, mCallerIdentity);
 
-        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        Boolean start = mDiscoveryProviderManager.startProviders();
         verify(mBluetoothController, never()).start();
         assertThat(start).isTrue();
     }
 
     @Test
     public void testStartProviders_chreOnlyChreAvailable_multipleFilters_bleProviderNotStarted() {
+        reset(mBluetoothController);
         when(mChreDiscoveryProvider.available()).thenReturn(true);
 
         ScanRequest scanRequest = new ScanRequest.Builder()
                 .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
-                .addScanFilter(getChreOnlyPresenceScanFilter())
-                .addScanFilter(getPresenceScanFilter()).build();
-        DiscoveryProviderManager.ScanListenerRecord record =
-                new DiscoveryProviderManager.ScanListenerRecord(
-                        scanRequest, mScanListener,
-                        mCallerIdentity, mScanListenerDeathRecipient);
-        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+                .addScanFilter(getChreOnlyPresenceScanFilter()).build();
+        mDiscoveryProviderManager.registerScanListener(scanRequest, mScanListener, mCallerIdentity);
 
-        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        Boolean start = mDiscoveryProviderManager.startProviders();
         verify(mBluetoothController, never()).start();
         assertThat(start).isTrue();
     }
 
     @Test
     public void testStartProviders_chreOnlyChreUnavailable_bleProviderNotStarted() {
+        reset(mBluetoothController);
         when(mChreDiscoveryProvider.available()).thenReturn(false);
 
         ScanRequest scanRequest = new ScanRequest.Builder()
                 .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
                 .addScanFilter(getChreOnlyPresenceScanFilter()).build();
-        DiscoveryProviderManager.ScanListenerRecord record =
-                new DiscoveryProviderManager.ScanListenerRecord(
-                        scanRequest, mScanListener,
-                        mCallerIdentity, mScanListenerDeathRecipient);
-        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+        mDiscoveryProviderManager.registerScanListener(scanRequest, mScanListener, mCallerIdentity);
 
-        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        Boolean start = mDiscoveryProviderManager.startProviders();
         verify(mBluetoothController, never()).start();
         assertThat(start).isFalse();
     }
@@ -218,17 +204,14 @@
     @Test
     public void testStartProviders_notChreOnlyChreAvailable_bleProviderNotStarted() {
         when(mChreDiscoveryProvider.available()).thenReturn(true);
+        reset(mBluetoothController);
 
         ScanRequest scanRequest = new ScanRequest.Builder()
                 .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
                 .addScanFilter(getPresenceScanFilter()).build();
-        DiscoveryProviderManager.ScanListenerRecord record =
-                new DiscoveryProviderManager.ScanListenerRecord(
-                        scanRequest, mScanListener,
-                        mCallerIdentity, mScanListenerDeathRecipient);
-        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+        mDiscoveryProviderManager.registerScanListener(scanRequest, mScanListener, mCallerIdentity);
 
-        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        Boolean start = mDiscoveryProviderManager.startProviders();
         verify(mBluetoothController, never()).start();
         assertThat(start).isTrue();
     }
@@ -236,17 +219,14 @@
     @Test
     public void testStartProviders_notChreOnlyChreUnavailable_bleProviderStarted() {
         when(mChreDiscoveryProvider.available()).thenReturn(false);
+        reset(mBluetoothController);
 
         ScanRequest scanRequest = new ScanRequest.Builder()
                 .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
                 .addScanFilter(getPresenceScanFilter()).build();
-        DiscoveryProviderManager.ScanListenerRecord record =
-                new DiscoveryProviderManager.ScanListenerRecord(
-                        scanRequest, mScanListener,
-                        mCallerIdentity, mScanListenerDeathRecipient);
-        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+        mDiscoveryProviderManager.registerScanListener(scanRequest, mScanListener, mCallerIdentity);
 
-        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        Boolean start = mDiscoveryProviderManager.startProviders();
         verify(mBluetoothController, atLeastOnce()).start();
         assertThat(start).isTrue();
     }
@@ -254,17 +234,14 @@
     @Test
     public void testStartProviders_chreOnlyChreUndetermined_bleProviderNotStarted() {
         when(mChreDiscoveryProvider.available()).thenReturn(null);
+        reset(mBluetoothController);
 
         ScanRequest scanRequest = new ScanRequest.Builder()
                 .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
                 .addScanFilter(getChreOnlyPresenceScanFilter()).build();
-        DiscoveryProviderManager.ScanListenerRecord record =
-                new DiscoveryProviderManager.ScanListenerRecord(
-                        scanRequest, mScanListener,
-                        mCallerIdentity, mScanListenerDeathRecipient);
-        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+        mDiscoveryProviderManager.registerScanListener(scanRequest, mScanListener, mCallerIdentity);
 
-        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        Boolean start = mDiscoveryProviderManager.startProviders();
         verify(mBluetoothController, never()).start();
         assertThat(start).isNull();
     }
@@ -272,17 +249,14 @@
     @Test
     public void testStartProviders_notChreOnlyChreUndetermined_bleProviderStarted() {
         when(mChreDiscoveryProvider.available()).thenReturn(null);
+        reset(mBluetoothController);
 
         ScanRequest scanRequest = new ScanRequest.Builder()
                 .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
                 .addScanFilter(getPresenceScanFilter()).build();
-        DiscoveryProviderManager.ScanListenerRecord record =
-                new DiscoveryProviderManager.ScanListenerRecord(
-                        scanRequest, mScanListener,
-                        mCallerIdentity, mScanListenerDeathRecipient);
-        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+        mDiscoveryProviderManager.registerScanListener(scanRequest, mScanListener, mCallerIdentity);
 
-        Boolean start = mDiscoveryProviderManager.startProviders(scanRequest);
+        Boolean start = mDiscoveryProviderManager.startProviders();
         verify(mBluetoothController, atLeastOnce()).start();
         assertThat(start).isTrue();
     }
@@ -291,22 +265,16 @@
     public void test_stopChreProvider_clearFilters() throws Exception {
         // Cannot use mocked ChreDiscoveryProvider,
         // so we cannot use class variable mDiscoveryProviderManager
-        ExecutorService executor = Executors.newSingleThreadExecutor();
         DiscoveryProviderManager manager =
-                new DiscoveryProviderManager(mContext, mInjector,
+                new DiscoveryProviderManager(mContext, mExecutor, mInjector,
                         mBleDiscoveryProvider,
                         new ChreDiscoveryProvider(
                                 mContext,
-                                new ChreCommunication(mInjector, mContext, executor), executor),
-                        mScanTypeScanListenerRecordMap);
+                                new ChreCommunication(mInjector, mContext, mExecutor), mExecutor));
         ScanRequest scanRequest = new ScanRequest.Builder()
                 .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
                 .addScanFilter(getPresenceScanFilter()).build();
-        DiscoveryProviderManager.ScanListenerRecord record =
-                new DiscoveryProviderManager.ScanListenerRecord(
-                        scanRequest, mScanListener,
-                        mCallerIdentity, mScanListenerDeathRecipient);
-        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+        manager.registerScanListener(scanRequest, mScanListener, mCallerIdentity);
         manager.startChreProvider(List.of(getPresenceScanFilter()));
         // This is an asynchronized process. The filters will be set in executor thread. So we need
         // to wait for some time to get the correct result.
@@ -328,21 +296,17 @@
     public void test_restartChreProvider() throws Exception {
         // Cannot use mocked ChreDiscoveryProvider,
         // so we cannot use class variable mDiscoveryProviderManager
-        ExecutorService executor = Executors.newSingleThreadExecutor();
         DiscoveryProviderManager manager =
-                new DiscoveryProviderManager(mContext, mInjector,
+                new DiscoveryProviderManager(mContext, mExecutor, mInjector,
                         mBleDiscoveryProvider,
                         new ChreDiscoveryProvider(
                                 mContext,
-                                new ChreCommunication(mInjector, mContext, executor), executor),
-                        mScanTypeScanListenerRecordMap);
+                                new ChreCommunication(mInjector, mContext, mExecutor), mExecutor));
         ScanRequest scanRequest = new ScanRequest.Builder()
                 .setScanType(SCAN_TYPE_NEARBY_PRESENCE)
                 .addScanFilter(getPresenceScanFilter()).build();
-        DiscoveryProviderManager.ScanListenerRecord record =
-                new DiscoveryProviderManager.ScanListenerRecord(scanRequest, mScanListener,
-                        mCallerIdentity, mScanListenerDeathRecipient);
-        mScanTypeScanListenerRecordMap.put(mIBinder, record);
+        manager.registerScanListener(scanRequest, mScanListener, mCallerIdentity);
+
         manager.startChreProvider(List.of(getPresenceScanFilter()));
         // This is an asynchronized process. The filters will be set in executor thread. So we need
         // to wait for some time to get the correct result.