Moving some initializations to the background thread

HandlerThread.getLooper blocks until the thread is ready. Instead
moving all looper dependency to the new thread itself.

Change-Id: I240e8c56b855a991433a7fe93875059e6dab146b
diff --git a/src/com/android/launcher3/Utilities.java b/src/com/android/launcher3/Utilities.java
index 43ccb79..1e023df 100644
--- a/src/com/android/launcher3/Utilities.java
+++ b/src/com/android/launcher3/Utilities.java
@@ -34,6 +34,7 @@
 import android.content.pm.ResolveInfo;
 import android.content.pm.ShortcutInfo;
 import android.content.res.Resources;
+import android.database.ContentObserver;
 import android.graphics.Bitmap;
 import android.graphics.Color;
 import android.graphics.Matrix;
@@ -44,6 +45,7 @@
 import android.graphics.drawable.ColorDrawable;
 import android.graphics.drawable.Drawable;
 import android.graphics.drawable.InsetDrawable;
+import android.net.Uri;
 import android.os.Build;
 import android.os.DeadObjectException;
 import android.os.Handler;
@@ -83,6 +85,7 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
+import java.util.function.Consumer;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -661,6 +664,18 @@
         return slop * slop;
     }
 
+    /**
+     * Helper method to create a content provider
+     */
+    public static ContentObserver newContentObserver(Handler handler, Consumer<Uri> command) {
+        return new ContentObserver(handler) {
+            @Override
+            public void onChange(boolean selfChange, Uri uri) {
+                command.accept(uri);
+            }
+        };
+    }
+
     private static class FixedSizeEmptyDrawable extends ColorDrawable {
 
         private final int mSize;
diff --git a/src/com/android/launcher3/states/RotationHelper.java b/src/com/android/launcher3/states/RotationHelper.java
index 5a60f53..ecf4f36 100644
--- a/src/com/android/launcher3/states/RotationHelper.java
+++ b/src/com/android/launcher3/states/RotationHelper.java
@@ -21,14 +21,9 @@
 import static android.util.DisplayMetrics.DENSITY_DEVICE_STABLE;
 
 import android.app.Activity;
-import android.content.ContentResolver;
 import android.content.SharedPreferences;
 import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
 import android.content.res.Resources;
-import android.database.ContentObserver;
-import android.os.Handler;
-import android.provider.Settings;
-import android.util.Log;
 
 import com.android.launcher3.R;
 import com.android.launcher3.Utilities;
@@ -43,16 +38,6 @@
 
     public static final String ALLOW_ROTATION_PREFERENCE_KEY = "pref_allowRotation";
 
-    private final ContentResolver mContentResolver;
-    private boolean mSystemAutoRotateEnabled;
-
-    private ContentObserver mSystemAutoRotateObserver = new ContentObserver(new Handler()) {
-        @Override
-        public void onChange(boolean selfChange) {
-            updateAutoRotateSetting();
-        }
-    };
-
     public static boolean getAllowRotationDefaultValue() {
         // If the device's pixel density was scaled (usually via settings for A11y), use the
         // original dimensions to determine if rotation is allowed of not.
@@ -106,20 +91,6 @@
         } else {
             mSharedPrefs = null;
         }
-
-        mContentResolver = activity.getContentResolver();
-    }
-
-    private void updateAutoRotateSetting() {
-        int autoRotateEnabled = 0;
-        try {
-            autoRotateEnabled = Settings.System.getInt(mContentResolver,
-                    Settings.System.ACCELEROMETER_ROTATION);
-        } catch (Settings.SettingNotFoundException e) {
-            Log.e(TAG, "autorotate setting not found", e);
-        }
-
-        mSystemAutoRotateEnabled = autoRotateEnabled == 1;
     }
 
     @Override
@@ -129,7 +100,6 @@
                 getAllowRotationDefaultValue());
         if (mHomeRotationEnabled != wasRotationEnabled) {
             notifyChange();
-            updateAutoRotateSetting();
         }
     }
 
@@ -165,11 +135,6 @@
         if (!mInitialized) {
             mInitialized = true;
             notifyChange();
-
-            mContentResolver.registerContentObserver(
-                    Settings.System.getUriFor(Settings.System.ACCELEROMETER_ROTATION),
-                    false, mSystemAutoRotateObserver);
-            updateAutoRotateSetting();
         }
     }
 
@@ -179,7 +144,6 @@
             if (mSharedPrefs != null) {
                 mSharedPrefs.unregisterOnSharedPreferenceChangeListener(this);
             }
-            mContentResolver.unregisterContentObserver(mSystemAutoRotateObserver);
         }
     }
 
@@ -225,9 +189,8 @@
     @Override
     public String toString() {
         return String.format("[mStateHandlerRequest=%d, mCurrentStateRequest=%d,"
-                + " mLastActivityFlags=%d, mIgnoreAutoRotateSettings=%b, mHomeRotationEnabled=%b,"
-                        + " mSystemAutoRotateEnabled=%b]",
+                + " mLastActivityFlags=%d, mIgnoreAutoRotateSettings=%b, mHomeRotationEnabled=%b]",
                 mStateHandlerRequest, mCurrentStateRequest, mLastActivityFlags,
-                mIgnoreAutoRotateSettings, mHomeRotationEnabled, mSystemAutoRotateEnabled);
+                mIgnoreAutoRotateSettings, mHomeRotationEnabled);
     }
 }
diff --git a/src/com/android/launcher3/util/BgObjectWithLooper.java b/src/com/android/launcher3/util/BgObjectWithLooper.java
new file mode 100644
index 0000000..1483c43
--- /dev/null
+++ b/src/com/android/launcher3/util/BgObjectWithLooper.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2020 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.launcher3.util;
+
+import android.os.Looper;
+
+import androidx.annotation.WorkerThread;
+
+/**
+ * Utility class to define an object which does most of it's processing on a
+ * dedicated background thread.
+ */
+public abstract class BgObjectWithLooper {
+
+    /**
+     * Start initialization of the object
+     */
+    public final void initializeInBackground(String threadName) {
+        new Thread(this::runOnThread, threadName).start();
+    }
+
+    private void runOnThread() {
+        Looper.prepare();
+        onInitialized(Looper.myLooper());
+        Looper.loop();
+    }
+
+    /**
+     * Called on the background thread to handle initialization
+     */
+    @WorkerThread
+    protected abstract void onInitialized(Looper looper);
+}