Fix two notification update issues on page navigation

content/browser/media/session/media_session_service_impl.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/media/session/media_session_service_impl.h"
 
 #include "content/browser/media/session/media_metadata_sanitizer.h"
 #include "content/browser/media/session/media_session_impl.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/public/browser/browser_thread.h"
@@ skipping 25 matching lines @@
   MediaSessionServiceImpl* impl =
       new MediaSessionServiceImpl(render_frame_host);
   impl->Bind(std::move(request));
 }
 
 RenderFrameHost* MediaSessionServiceImpl::GetRenderFrameHost() {
   return RenderFrameHost::FromID(render_frame_process_id_,
                                  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);
 }
 
 void MediaSessionServiceImpl::SetPlaybackState(
     blink::mojom::MediaSessionPlaybackState state) {
   playback_state_ = state;
   MediaSessionImpl* session = GetMediaSession();
   if (session)
@@ skipping 49 matching lines @@
   return MediaSessionImpl::Get(contents);
 }
 
 void MediaSessionServiceImpl::Bind(
     blink::mojom::MediaSessionServiceRequest request) {
   binding_.reset(new mojo::Binding<blink::mojom::MediaSessionService>(
       this, std::move(request)));
 }
 
 }  // namespace content