Refactor SettingsLib to remove redundant resources conditionally

Bug: 320878675
Test: manual
Change-Id: I77b3eb4cc2edbbfa6788e53004e370d49da0c0c0
diff --git a/packages/SettingsLib/AvatarPicker/src/ThreadUtils.java b/packages/SettingsLib/AvatarPicker/src/ThreadUtils.java
new file mode 100644
index 0000000..dc19e66
--- /dev/null
+++ b/packages/SettingsLib/AvatarPicker/src/ThreadUtils.java
@@ -0,0 +1,115 @@
+/*
+ * Copyright (C) 2024 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.settingslib.avatarpicker;
+
+import android.os.Handler;
+import android.os.Looper;
+
+import androidx.annotation.NonNull;
+
+import com.google.common.util.concurrent.ListenableFuture;
+import com.google.common.util.concurrent.ListeningExecutorService;
+import com.google.common.util.concurrent.MoreExecutors;
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.Executors;
+
+// copied from SettinsLib/utils
+public class ThreadUtils {
+
+    private static volatile Thread sMainThread;
+    private static volatile Handler sMainThreadHandler;
+    private static volatile ListeningExecutorService sListeningService;
+
+    /**
+     * Returns true if the current thread is the UI thread.
+     */
+    public static boolean isMainThread() {
+        if (sMainThread == null) {
+            sMainThread = Looper.getMainLooper().getThread();
+        }
+        return Thread.currentThread() == sMainThread;
+    }
+
+    /**
+     * Returns a shared UI thread handler.
+     */
+    @NonNull
+    public static Handler getUiThreadHandler() {
+        if (sMainThreadHandler == null) {
+            sMainThreadHandler = new Handler(Looper.getMainLooper());
+        }
+
+        return sMainThreadHandler;
+    }
+
+    /**
+     * Checks that the current thread is the UI thread. Otherwise throws an exception.
+     */
+    public static void ensureMainThread() {
+        if (!isMainThread()) {
+            throw new RuntimeException("Must be called on the UI thread");
+        }
+    }
+
+    /**
+     * Posts runnable in background using shared background thread pool.
+     *
+     * @return A future of the task that can be monitored for updates or cancelled.
+     */
+    @SuppressWarnings("rawtypes")
+    @NonNull
+    public static ListenableFuture postOnBackgroundThread(@NonNull Runnable runnable) {
+        return getBackgroundExecutor().submit(runnable);
+    }
+
+    /**
+     * Posts callable in background using shared background thread pool.
+     *
+     * @return A future of the task that can be monitored for updates or cancelled.
+     */
+    @NonNull
+    public static <T> ListenableFuture<T> postOnBackgroundThread(@NonNull Callable<T> callable) {
+        return getBackgroundExecutor().submit(callable);
+    }
+
+    /**
+     * Posts the runnable on the main thread.
+     *
+     * @deprecated moving work to the main thread should be done via the main executor provided to
+     * {@link com.google.common.util.concurrent.FutureCallback} via
+     * {@link android.content.Context#getMainExecutor()} or by calling an SDK method such as
+     * {@link android.app.Activity#runOnUiThread(Runnable)} or
+     * {@link android.content.Context#getMainThreadHandler()} where appropriate.
+     */
+    @Deprecated
+    public static void postOnMainThread(@NonNull Runnable runnable) {
+        getUiThreadHandler().post(runnable);
+    }
+
+    /**
+     * Provides a shared {@link ListeningExecutorService} created using a fixed thread pool executor
+     */
+    @NonNull
+    public static synchronized ListeningExecutorService getBackgroundExecutor() {
+        if (sListeningService == null) {
+            sListeningService = MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(
+                    Runtime.getRuntime().availableProcessors()));
+        }
+        return sListeningService;
+    }
+}