[Chromecast] Encapsulate request/abandonAudioFocus.

This allows all users of CastAudioManager to use
request/abandonAudioFocus() without a @SuppressWarnings
annotation.

This paves the way for encapsulating SDK-dependent
implementation details for AudioManager in CastAudioManager,
reducing the number of SDK version checks that need to be
performed throughout the codebase.

Bug: Internal b/70158727
Test: build cast_shell_java
      Run internal junit tests
Merge-With: eureka-internal/127089

Change-Id: Iacd88d1d2e298ddd3b9ae6eb2749f0a43b5ede77
Reviewed-on: https://chromium-review.googlesource.com/806929
Commit-Queue: Simeon Anfinrud <sanfin@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521547}

chromecast/browser/android/apk/src/org/chromium/chromecast/shell/CastAudioManager.java

@@ -12,14 +12,41 @@ import android.media.AudioManager;
  * Muting and unmuting streams must be invoke on the same AudioManager instance.
  */
 public class CastAudioManager {
+    // TODO(sanfin): This class should encapsulate SDK-dependent implementation details of
+    // android.media.AudioManager.
+    private static CastAudioManager sInstance = null;
 
-    private static AudioManager sAudioManager = null;
-
-    public static AudioManager getAudioManager(Context context) {
-        if (sAudioManager == null) {
-            sAudioManager = (AudioManager) context.getApplicationContext()
-                .getSystemService(Context.AUDIO_SERVICE);
+    public static CastAudioManager getAudioManager(Context context) {
+        if (sInstance == null) {
+            sInstance = new CastAudioManager(
+                    (AudioManager) context.getApplicationContext().getSystemService(
+                            Context.AUDIO_SERVICE));
         }
-        return sAudioManager;
+        return sInstance;
+    }
+
+    private final AudioManager mAudioManager;
+
+    private CastAudioManager(AudioManager audioManager) {
+        mAudioManager = audioManager;
+    }
+
+    // TODO(sanfin): Use the AudioFocusRequest version on O and above.
+    @SuppressWarnings("deprecation")
+    public int requestAudioFocus(
+            AudioManager.OnAudioFocusChangeListener l, int streamType, int durationHint) {
+        return mAudioManager.requestAudioFocus(l, streamType, durationHint);
+    }
+
+    // TODO(sanfin): Use the AudioFocusRequest version on O and above.
+    @SuppressWarnings("deprecation")
+    public int abandonAudioFocus(AudioManager.OnAudioFocusChangeListener l) {
+        return mAudioManager.abandonAudioFocus(l);
+    }
+
+    // TODO(sanfin): Do not expose this. All needed AudioManager methods can be adapted with
+    // CastAudioManager.
+    public AudioManager getInternal() {
+        return mAudioManager;
     }
 }

chromecast/browser/android/apk/src/org/chromium/chromecast/shell/CastWebContentsActivity.java

@@ -51,7 +51,7 @@ public class CastWebContentsActivity extends Activity {
     private BroadcastReceiver mWindowDestroyedBroadcastReceiver;
     private BroadcastReceiver mScreenOffBroadcastReceiver;
     private FrameLayout mCastWebContentsLayout;
-    private AudioManager mAudioManager;
+    private CastAudioManager mAudioManager;
     private ContentViewRenderView mContentViewRenderView;
     private WindowAndroid mWindow;
     private ContentViewCore mContentViewCore;
@@ -334,7 +334,7 @@ public class CastWebContentsActivity extends Activity {
 
     @SuppressWarnings("deprecation")
     private void releaseStreamMuteIfNecessary() {
-        AudioManager audioManager = CastAudioManager.getAudioManager(this);
+        AudioManager audioManager = mAudioManager.getInternal();
         boolean isMuted = false;
         try {
             isMuted = (Boolean) audioManager.getClass()

chromecast/browser/android/apk/src/org/chromium/chromecast/shell/CastWebContentsService.java

@@ -32,7 +32,7 @@ public class CastWebContentsService extends Service {
     private static final int CAST_NOTIFICATION_ID = 100;
 
     private String mInstanceId;
-    private AudioManager mAudioManager;
+    private CastAudioManager mAudioManager;
     private WindowAndroid mWindow;
     private ContentViewCore mContentViewCore;
     private ContentView mContentView;