Very early implementation for HTMLMediaElement / Web Audio API integration

content/renderer/render_audiosourceprovider.h

Index: content/renderer/render_audiosourceprovider.h
===================================================================
--- content/renderer/render_audiosourceprovider.h	(revision 0)
+++ content/renderer/render_audiosourceprovider.h	(revision 0)
@@ -0,0 +1,47 @@
+// Copyright (c) 2011 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_RENDERER_RENDERER_WEBAUDIOSOURCEPROVIDER_IMPL_H_
+#define CONTENT_RENDERER_RENDERER_WEBAUDIOSOURCEPROVIDER_IMPL_H_
+
+#include <vector>
+
+#include "media/filters/audio_renderer_sink.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebAudioSourceProvider.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebVector.h"
+
+// RenderAudioSourceProvider provides a bridge between classes:
+//     WebKit::WebAudioSourceProvider <---> media::AudioRendererSink
+//
+// The idea is that some code within WebKit periodically calls provideInput()
+// to render a certain number of audio sample-frames.  provideInput()
+// uses its callback to get this data, and then massages it into the form
+// required by provideInput().
+
+class RenderAudioSourceProvider
+    : public WebKit::WebAudioSourceProvider,
+      public media::AudioRendererSink {
+ public:
+  RenderAudioSourceProvider(media::AudioRendererSink::RenderCallback* callback);
+  virtual ~RenderAudioSourceProvider() { }
+
+  // WebKit::WebAudioSourceProvider implementation.
+  // WebKit calls this to get the rendered audio stream.
+  virtual void provideInput(const WebKit::WebVector<float*>& audio_data,
+                            size_t number_of_frames);
+
+  // AudioSink implementation.
+  virtual bool Start();
+  virtual bool Stop();
+  virtual bool SetVolume(double volume);
+
+ private:
+  bool is_running_;
+  double volume_;
+  media::AudioRendererSink::RenderCallback* callback_;
+  
+  DISALLOW_COPY_AND_ASSIGN(RenderAudioSourceProvider);
+};
+
+#endif  // CONTENT_RENDERER_RENDERER_WEBAUDIOSOURCEPROVIDER_IMPL_H_