MediaSession: Stop observers on MediaSession destruction

content/browser/media/session/media_session_impl.cc

Index: content/browser/media/session/media_session_impl.cc
diff --git a/content/browser/media/session/media_session_impl.cc b/content/browser/media/session/media_session_impl.cc
index e2e554653b7c795504b18975930c0d1d8b468722..222701e81c0411222060cc19fb5bc558f55a4d03 100644
--- a/content/browser/media/session/media_session_impl.cc
+++ b/content/browser/media/session/media_session_impl.cc
@@ -93,8 +93,10 @@ MediaSessionImpl::~MediaSessionImpl() {
   DCHECK(pepper_players_.empty());
   DCHECK(one_shot_players_.empty());
   DCHECK(audio_focus_state_ == State::INACTIVE);
-  for (auto& observer : observers_)
+  for (auto& observer : observers_) {
     observer.MediaSessionDestroyed();
+    observer.StopObserving();
+  }
 }
 
 void MediaSessionImpl::WebContentsDestroyed() {