Adds AudioDevice factory for all audio clients in Chrome

content/renderer/media/audio_device.h

 // Copyright (c) 2012 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.
 //
 // Audio rendering unit utilizing audio output stream provided by browser
 // process through IPC.
 //
 // Relationship of classes.
 //
 //  AudioOutputController                AudioDevice
@@ skipping 58 matching lines @@
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "base/shared_memory.h"
 #include "content/common/content_export.h"
 #include "content/renderer/media/audio_device_thread.h"
 #include "content/renderer/media/audio_message_filter.h"
 #include "content/renderer/media/scoped_loop_observer.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/audio_renderer_sink.h"
 
+class AudioMessageFilter;
+
 namespace media {
 class AudioParameters;
 }
 
 class CONTENT_EXPORT AudioDevice
     : NON_EXPORTED_BASE(public media::AudioRendererSink),
       public AudioMessageFilter::Delegate,
       NON_EXPORTED_BASE(public ScopedLoopObserver) {
  public:
   // Methods called on main render thread -------------------------------------
 
   // Minimal constructor where Initialize() must be called later.
-  AudioDevice();
-
-  AudioDevice(const media::AudioParameters& params, RenderCallback* callback);
+  explicit AudioDevice(AudioMessageFilter* filter);

[Chris Rogers, 2012/06/14 17:41:44]

This is leaking internal implementation details for AudioDevice into the public
interface which is not a good idea.  The whole purpose of the AudioDevice
interface is to shield the client from any particular low-level details such as
this.  With this change, any client of AudioDevice must now get entangled into
AudioMessageFilters.

[tommi (sloooow) - chröme, 2012/06/16 09:09:06]

AudioDevice is the implementation, media::AudioRendererSink is the interface
(which btw should have been named media::AudioRendererSinkInterface in
accordance with the style guide).  Unless this constructor is a part of the
interface, then there's nothing being leaked.

 
   // AudioRendererSink implementation.
   virtual void Initialize(const media::AudioParameters& params,
                           RenderCallback* callback) OVERRIDE;
   virtual void Start() OVERRIDE;
   virtual void Stop() OVERRIDE;
   virtual void Play() OVERRIDE;
   virtual void Pause(bool flush) OVERRIDE;
   virtual bool SetVolume(double volume) OVERRIDE;
   virtual void GetVolume(double* volume) OVERRIDE;
@@ skipping 57 matching lines @@
   // guard to control stopping and starting the audio thread.
   base::Lock audio_thread_lock_;
   AudioDeviceThread audio_thread_;
   scoped_ptr<AudioDevice::AudioThreadCallback> audio_callback_;
 
 
   DISALLOW_COPY_AND_ASSIGN(AudioDevice);
 };
 
 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_DEVICE_H_