Added initial set of logging for AudioOutputController.

content/browser/renderer_host/media/audio_output_delegate_impl.h

 // 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_DELEGATE_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_DELEGATE_IMPL_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 53 matching lines @@
   void OnPlayStream() override;
   void OnPauseStream() override;
   void OnSetVolume(double volume) override;
 
  private:
   class ControllerEventHandler;
   friend class AudioOutputDelegateTest;
 
   void SendCreatedNotification();
   void OnError();
+  static void DoLog(int stream_id, const std::string& msg);

[liberato (no reviews please), 2017/05/30 16:53:34]

please add a comment about why this needs to be static.  it's a little subtle.

[ossu-chromium, 2017/05/31 11:16:27]

I've looked at this again and I think it would be even better if I just folded
this into OnLog as a lambda instead. There's no reason this function needs to be
in AudioOutputDelegateImpl nor publicly visible.

   void UpdatePlayingState(bool playing);
   media::AudioOutputController* GetControllerForTesting() const;
 
   // This is the event handler which |this| send notifications to.
   EventHandler* subscriber_;
   std::unique_ptr<media::AudioLog> const audio_log_;
   // |controller_event_handler_| proxies events from controller to |this|.
   // |controller_event_handler_|, |reader_| and |mirroring_manager_| will
   // outlive |this|, see the destructor for details.
   std::unique_ptr<ControllerEventHandler> controller_event_handler_;
   std::unique_ptr<AudioSyncReader> reader_;
   AudioMirroringManager* mirroring_manager_;
   scoped_refptr<media::AudioOutputController> controller_;
   const int stream_id_;
   const int render_frame_id_;
   const int render_process_id_;
 
   // This flag ensures that we only send OnStreamStateChanged notifications
   // and (de)register with the stream monitor when the state actually changes.
   bool playing_ = false;
   base::WeakPtrFactory<AudioOutputDelegateImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioOutputDelegateImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_OUTPUT_DELEGATE_IMPL_H_