Fix an issue that audio and video may run out of sync

media/base/android/java/src/org/chromium/media/MediaCodecBridge.java

Index: media/base/android/java/src/org/chromium/media/MediaCodecBridge.java
diff --git a/media/base/android/java/src/org/chromium/media/MediaCodecBridge.java b/media/base/android/java/src/org/chromium/media/MediaCodecBridge.java
index cfcebb01517423c635dea67f66eba8df300905ae..5eb7b5bcc6dd59904a80fe2fc432476d8b31c872 100644
--- a/media/base/android/java/src/org/chromium/media/MediaCodecBridge.java
+++ b/media/base/android/java/src/org/chromium/media/MediaCodecBridge.java
@@ -285,6 +285,8 @@ class MediaCodecBridge {
         try {
             mFlushed = true;
             if (mAudioTrack != null) {
+                // Need to call pause() here, or otherwise flush() is a no-op.
+                mAudioTrack.pause();
                 mAudioTrack.flush();
             }
             mMediaCodec.flush();
@@ -525,18 +527,36 @@ class MediaCodecBridge {
         return false;
     }
 
+    /**
+     *  Play the audio buffer that is passed in.
+     *
+     *  @param buf Audio buffer to be rendered.
+     *  @return The number of frames that have already been consumed by the
+     *  hardware. This number resets to 0 after each flush call.
+     */
     @CalledByNative
-    private void playOutputBuffer(byte[] buf) {
-        if (mAudioTrack != null) {
-            if (AudioTrack.PLAYSTATE_PLAYING != mAudioTrack.getPlayState()) {
-                mAudioTrack.play();
-            }
-            int size = mAudioTrack.write(buf, 0, buf.length);
-            if (buf.length != size) {
-                Log.i(TAG, "Failed to send all data to audio output, expected size: " +
-                        buf.length + ", actual size: " + size);
-            }
+    private long playOutputBuffer(byte[] buf) {
+        if (mAudioTrack == null) {
+            return 0;
+        }
+
+        if (AudioTrack.PLAYSTATE_PLAYING != mAudioTrack.getPlayState()) {
+            mAudioTrack.play();
+        }
+        int size = mAudioTrack.write(buf, 0, buf.length);
+        if (buf.length != size) {
+            Log.i(TAG, "Failed to send all data to audio output, expected size: " +
+                    buf.length + ", actual size: " + size);
         }
+        // TODO(qinmin): Returning the head position allows us to estimate
+        // the current presentation time in native code. However, it is
+        // better to use AudioTrack.getCurrentTimestamp() to get the last
+        // known time when a frame is played. However, we will need to
+        // convert the java nano time to C++ timestamp.
+        // If the stream runs too long, getPlaybackHeadPosition() could
+        // overflow. AudioTimestampHelper in MediaSourcePlayer has the same
+        // issue. See http://crbug.com/358801.
+        return mAudioTrack.getPlaybackHeadPosition();
     }
 
     @CalledByNative