Refactor content::RenderAudioSourceProvider as webkit_media::WebAudioSourceProviderImpl.

webkit/media/webaudiosourceprovider_impl.h

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright (c) 2013 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.
-//
-// RenderAudioSourceProvider provides a bridge between classes:
+
+#ifndef WEBKIT_MEDIA_WEBAUDIOSOURCEPROVIDER_IMPL_H_
+#define WEBKIT_MEDIA_WEBAUDIOSOURCEPROVIDER_IMPL_H_
+
+#include "base/synchronization/lock.h"
+#include "media/base/audio_renderer_sink.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebAudioSourceProvider.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebVector.h"
+
+namespace WebKit {
+class WebAudioSourceProviderClient;
+}
+
+namespace webkit_media {
+
+// WebAudioSourceProviderImpl provides a bridge between classes:
 //     WebKit::WebAudioSourceProvider <---> media::AudioRendererSink
 //
-// RenderAudioSourceProvider is a "sink" of audio, and uses a default
-// AudioOutputDevice if a client has not explicitly been set.
-//
-// WebKit optionally sets a client, and then periodically calls provideInput()
-// to render a certain number of audio sample-frames.  provideInput()
-// uses the renderer to get this data, and then massages it into the form
-// required by provideInput().  In this case, the default AudioOutputDevice
-// is no longer used.
+// WebAudioSourceProviderImpl wraps an existing audio sink that is used unless
+// WebKit has set a client via setClient(). While a client is set WebKit will
+// periodically call provideInput() to render a certain number of audio
+// sample-frames using the sink's RenderCallback to get the data.
 //
 // THREAD SAFETY:
 // It is assumed that the callers to setClient() and provideInput()
 // implement appropriate locking for thread safety when making
 // these calls.  This happens in WebKit.
-
-#ifndef CONTENT_RENDERER_MEDIA_RENDER_AUDIOSOURCEPROVIDER_H_
-#define CONTENT_RENDERER_MEDIA_RENDER_AUDIOSOURCEPROVIDER_H_
-
-#include "base/synchronization/lock.h"
-#include "media/base/audio_renderer_sink.h"
-#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebVector.h"
-#include "third_party/WebKit/Source/WebKit/chromium/public/WebAudioSourceProvider.h"
-
-namespace WebKit {
-class WebAudioSourceProviderClient;
-}
-
-namespace content {
-
-class RenderAudioSourceProvider
+class WebAudioSourceProviderImpl
     : public WebKit::WebAudioSourceProvider,
       public media::AudioRendererSink {
  public:
-  explicit RenderAudioSourceProvider(int source_render_view_id);
+  explicit WebAudioSourceProviderImpl(
+      const scoped_refptr<media::AudioRendererSink>& sink);
 
   // WebKit::WebAudioSourceProvider implementation.
-
-  // WebKit calls setClient() if it desires to take control of the rendered
-  // audio stream.  We call client's setFormat() when the audio stream format
-  // is known.
   virtual void setClient(WebKit::WebAudioSourceProviderClient* client);
-
-  // If setClient() has been called, then WebKit calls provideInput()
-  // periodically to get the rendered audio stream.
   virtual void provideInput(const WebKit::WebVector<float*>& audio_data,
                             size_t number_of_frames);
 
-  // AudioRendererSink implementation.
+  // media::AudioRendererSink implementation.
   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 Initialize(const media::AudioParameters& params,
                           RenderCallback* renderer) OVERRIDE;
 
  protected:
-  virtual ~RenderAudioSourceProvider();
+  virtual ~WebAudioSourceProviderImpl();
 
  private:
   // Set to true when Initialize() is called.
   bool is_initialized_;
   int channels_;
   int sample_rate_;
 
+  // Tracks if |sink_| has been instructed to consume audio.
   bool is_running_;
+
+  // Where audio comes from.
   media::AudioRendererSink::RenderCallback* renderer_;
+
+  // When set via setClient() it overrides |sink_| for consuming audio.
   WebKit::WebAudioSourceProviderClient* client_;
 
-  // Protects access to sink_
+  // Where audio ends up unless overridden by |client_|.
   base::Lock sink_lock_;
+  scoped_refptr<media::AudioRendererSink> sink_;

[miu, 2013/01/09 18:48:35]

nit: Since sink_ is set via the ctor initializer list and never changed anywhere
else in the class, consider making the type const scoped_refptr<...> here.

 
-  // default_sink_ is the default sink.
-  scoped_refptr<media::AudioRendererSink> default_sink_;
-
-  DISALLOW_IMPLICIT_CONSTRUCTORS(RenderAudioSourceProvider);
+  DISALLOW_IMPLICIT_CONSTRUCTORS(WebAudioSourceProviderImpl);
 };
 
-}  // namespace content
+}  // namespace webkit_media
 
-#endif  // CONTENT_RENDERER_MEDIA_RENDER_AUDIOSOURCEPROVIDER_H_
+#endif  // WEBKIT_MEDIA_WEBAUDIOSOURCEPROVIDER_IMPL_H_