NOT FOR LANDING Implement WebMediaSession

content/browser/media/android/media_session.cc

Index: content/browser/media/android/media_session.cc
diff --git a/content/browser/media/android/media_session.cc b/content/browser/media/android/media_session.cc
index a8b64efec4c97877fd06bbb644fb14dc63781919..0c66243dc03665c0debe241efc5934416a46be09 100644
--- a/content/browser/media/android/media_session.cc
+++ b/content/browser/media/android/media_session.cc
@@ -55,6 +55,26 @@ MediaSession::~MediaSession() {
   DCHECK(audio_focus_state_ == State::INACTIVE);
 }
 
+bool MediaSession::Activate() {
+  if (audio_focus_state_ == State::ACTIVE)
+    return true;
+
+  const Type type = Type::Content;
+  if (!RequestSystemAudioFocus(type))
+    return false;
+
+  audio_focus_state_ = State::ACTIVE;
+  audio_focus_type_ = type;
+  UpdateWebContents();
+
+  return true;
+}
+
+void MediaSession::Deactivate() {
+  AbandonSystemAudioFocusIfNeeded();

[mlamouri (slow - plz ping), 2015/08/24 12:55:24]

Looking at that code, it's a bit odd that RequestSystemAudioFocus() doesn't
update audio_focus_state and doesn't call UpdateWebContents() but
AbandonSystemAudioFocusIfNeeded() does.

[philipj_slow, 2015/08/26 07:39:48]

Yes, this doesn't make any sense, I just hacked until it was possible to get a
notification showing using the API. If we split the responsibility for
monitoring media players out of this class, then I think we would end up with a
much cleaner Activate() and Deactivate(), that would be the only places to
request or abandon audio focus.

+  DCHECK(audio_focus_state_ == State::INACTIVE);
+}
+
 bool MediaSession::AddPlayer(MediaSessionObserver* observer,
                              int player_id,
                              Type type) {