Fix two notification update issues on page navigation

content/browser/media/session/media_session_service_impl.cc

Index: content/browser/media/session/media_session_service_impl.cc
diff --git a/content/browser/media/session/media_session_service_impl.cc b/content/browser/media/session/media_session_service_impl.cc
index cf452e2204df634b8f8e29dc8b873006c40c9484..f7cf58d65d15965a7dadd110d3b5240f4fb9e46d 100644
--- a/content/browser/media/session/media_session_service_impl.cc
+++ b/content/browser/media/session/media_session_service_impl.cc
@@ -43,6 +43,12 @@ RenderFrameHost* MediaSessionServiceImpl::GetRenderFrameHost() {
                                  render_frame_routing_id_);
 }
 
+void MediaSessionServiceImpl::Reset() {
+  playback_state_ = blink::mojom::MediaSessionPlaybackState::NONE;

[whywhat, 2017/02/28 21:26:56]

nit: I wonder if you should actually call
SetPlaybackState/SetMetadata/DisableAction so the java part is guaranteed to be
in sync. Currently it's only because you have that code in MediaSessionTabHelper
that does the same.

[Zhiqiang Zhang (Slow), 2017/02/28 22:13:10]

Done.
Also I think the actions should be cleared in one run, so I added a private
method `ClearActions()`.

+  metadata_ = base::nullopt;
+  actions_.clear();
+}
+
 void MediaSessionServiceImpl::SetClient(
     blink::mojom::MediaSessionClientPtr client) {
   client_ = std::move(client);