Relax rules for media apps to stay on RemoteControlDisplay

The playback of notification would make the display of the
 RemoteControlClient disappear from the lockscreen.

Fixed by modifying which AudioFocus owner to consider when
 reevaluating how the RemoteControlDisplay needs to be updated:
 use the first (starting from the top of the AudioFocus stack) that
 uses STREAM_MUSIC, or that uses any other stream type for a short
 period.

Change-Id: Id7cef00c5eed1f6ebfa59634eea8e2c9b2f3f5eb

Author: jmtrivi

media/java/android/media/AudioService.java

@@ -3660,9 +3660,10 @@ private void dumpFocusStack(PrintWriter pw) {
             Iterator<FocusStackEntry> stackIterator = mFocusStack.iterator();
             while(stackIterator.hasNext()) {
                 FocusStackEntry fse = stackIterator.next();
-                pw.println("     source:" + fse.mSourceRef + " -- client: " + fse.mClientId
+                pw.println("  source:" + fse.mSourceRef + " -- client: " + fse.mClientId
                         + " -- duration: " + fse.mFocusChangeType
-                        + " -- uid: " + fse.mCallingUid);
+                        + " -- uid: " + fse.mCallingUid
+                        + " -- stream: " + fse.mStreamType);
             }
         }
     }
@@ -4022,7 +4023,7 @@ private void filterVoiceInputKeyEvent(KeyEvent keyEvent, boolean needWakeLock) {
                 startVoiceBasedInteractions(needWakeLock);
                 break;
             case VOICEBUTTON_ACTION_SIMULATE_KEY_PRESS:
-                if (DEBUG_RC) Log.v(TAG, "   send simulated key event");
+                if (DEBUG_RC) Log.v(TAG, "   send simulated key event, wakelock=" + needWakeLock);
                 sendSimulatedMediaButtonEvent(keyEvent, needWakeLock);
                 break;
         }
@@ -4654,17 +4655,40 @@ private void checkUpdateRemoteControlDisplay_syncAfRcs(int infoChangedFlags) {
             clearRemoteControlDisplay_syncAfRcs();
             return;
         }
-        // if the top of the two stacks belong to different packages, there is a mismatch, clear
+
+        // determine which entry in the AudioFocus stack to consider, and compare against the
+        // top of the stack for the media button event receivers : simply using the top of the
+        // stack would make the entry disappear from the RemoteControlDisplay in conditions such as
+        // notifications playing during music playback.
+        // crawl the AudioFocus stack until an entry is found with the following characteristics:
+        // - focus gain on STREAM_MUSIC stream
+        // - non-transient focus gain on a stream other than music
+        FocusStackEntry af = null;
+        Iterator<FocusStackEntry> stackIterator = mFocusStack.iterator();
+        while(stackIterator.hasNext()) {
+            FocusStackEntry fse = (FocusStackEntry)stackIterator.next();
+            if ((fse.mStreamType == AudioManager.STREAM_MUSIC)
+                    || (fse.mFocusChangeType == AudioManager.AUDIOFOCUS_GAIN)) {
+                af = fse;
+                break;
+            }
+        }
+        if (af == null) {
+            clearRemoteControlDisplay_syncAfRcs();
+            return;
+        }
+
+        // if the audio focus and RC owners belong to different packages, there is a mismatch, clear
         if ((mRCStack.peek().mCallingPackageName != null)
-                && (mFocusStack.peek().mPackageName != null)
+                && (af.mPackageName != null)
                 && !(mRCStack.peek().mCallingPackageName.compareTo(
-                        mFocusStack.peek().mPackageName) == 0)) {
+                        af.mPackageName) == 0)) {
             clearRemoteControlDisplay_syncAfRcs();
             return;
         }
         // if the audio focus didn't originate from the same Uid as the one in which the remote
         //   control information will be retrieved, clear
-        if (mRCStack.peek().mCallingUid != mFocusStack.peek().mCallingUid) {
+        if (mRCStack.peek().mCallingUid != af.mCallingUid) {
             clearRemoteControlDisplay_syncAfRcs();
             return;
         }