[MediaSession, Android] Adding visibility tests for MediaSession

content/browser/media/session/media_session.cc

 // Copyright 2015 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.h"
 
 #include "content/browser/media/session/media_session_delegate.h"
 #include "content/browser/media/session/media_session_observer.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/public/browser/web_contents.h"
@@ skipping 191 matching lines @@
   // TODO(mlamouri): should be == State::SUSPENDED.
   return audio_focus_state_ != State::ACTIVE;
 }
 
 bool MediaSession::IsControllable() const {
   // Only content type media session can be controllable unless it is inactive.
   return audio_focus_state_ != State::INACTIVE &&
          audio_focus_type_ == Type::Content;
 }
 
+scoped_ptr<base::CallbackList<void(MediaSession::State)>::Subscription>
+MediaSession::RegisterMediaSessionStateChangedCallbackForTest(
+    const StateChangedCallback& cb) {
+  return media_session_state_listeners_.Add(cb);
+}
+
 void MediaSession::SetDelegateForTests(
     scoped_ptr<MediaSessionDelegate> delegate) {
   delegate_ = std::move(delegate);
 }
 
 bool MediaSession::IsActiveForTest() const {
   return audio_focus_state_ == State::ACTIVE;
 }
 
 MediaSession::Type MediaSession::audio_focus_type_for_test() const {
@@ skipping 88 matching lines @@
   if (audio_focus_state_ == State::INACTIVE || !players_.empty())
     return;
 
   delegate_->AbandonAudioFocus();
 
   SetAudioFocusState(State::INACTIVE);
   UpdateWebContents();
 }
 
 void MediaSession::UpdateWebContents() {
+  media_session_state_listeners_.Notify(audio_focus_state_);
   static_cast<WebContentsImpl*>(web_contents())->OnMediaSessionStateChanged();
 }
 
 void MediaSession::SetAudioFocusState(State audio_focus_state) {
   if (audio_focus_state == audio_focus_state_)
     return;
 
   audio_focus_state_ = audio_focus_state;
   switch (audio_focus_state_) {
     case State::ACTIVE:
       uma_helper_.OnSessionActive();
       break;
     case State::SUSPENDED:
       uma_helper_.OnSessionSuspended();
       break;
     case State::INACTIVE:
       uma_helper_.OnSessionInactive();
       break;
   }
 }
 
 }  // namespace content