Listen to the audio focus event for MSE/EME

media/base/android/media_source_player.cc

Index: media/base/android/media_source_player.cc
diff --git a/media/base/android/media_source_player.cc b/media/base/android/media_source_player.cc
index 4e744fb8d14a8de3a2e77973fa685ceb9880704d..35ab8454fb5d08e80b203e00b1a66985f42e357f 100644
--- a/media/base/android/media_source_player.cc
+++ b/media/base/android/media_source_player.cc
@@ -194,6 +194,7 @@ void MediaSourcePlayer::Release() {
   playing_ = false;
 
   decoder_starvation_callback_.Cancel();
+  DetachListener();
 }
 
 void MediaSourcePlayer::SetVolume(double volume) {
@@ -230,6 +231,7 @@ void MediaSourcePlayer::StartInternal() {
   // be clear (not encrypted) or encrypted with different keys. So
   // |is_waiting_for_key_| condition may not be true anymore.
   is_waiting_for_key_ = false;
+  AttachListener(NULL);
 
   SetPendingEvent(PREFETCH_REQUEST_EVENT_PENDING);
   ProcessPendingEvents();