Adds AudioDevice factory for all audio clients in Chrome

content/renderer/media/audio_device_factory.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.
+
+#ifndef CONTENT_RENDERER_MEDIA_AUDIO_DEVICE_FACTORY_H_
+#define CONTENT_RENDERER_MEDIA_AUDIO_DEVICE_FACTORY_H_
+#pragma once
+
+#include "base/basictypes.h"
+#include "content/common/content_export.h"
+
+namespace media {
+class AudioRendererSink;
+}
+
+// A factory for creating AudioRendererSinks. There is a global factory
+// function that can be installed for the purposes of testing to provide
+// a specialized AudioRendererSink class.
+// This class uses the same pattern as content::RenderViewHostFactory.
+class AudioDeviceFactory {
+ public:
+  // Creates an AudioRendererSink using the currently registered factory,
+  // or the default one if no factory is registered. Ownership of the returned
+  // pointer will be passed to the caller.
+  static media::AudioRendererSink* Create();
+
+  // Returns true if there is currently a globally-registered factory.
+  static bool has_factory() {
+    return !!factory_;
+  }
+
+ protected:
+  AudioDeviceFactory() {}
+  virtual ~AudioDeviceFactory() {}
+
+  // You can derive from this class and specify an implementation for this
+  // function to create a different kind of AudioRendererSink for testing.
+  virtual media::AudioRendererSink* CreateAudioDevice() = 0;
+
+  // Registers your factory to be called when new AudioRendererSinks are
+  // created. We have only one global factory, so there must be no factory
+  // registered before the call. This class does NOT take ownership of the
+  // pointer.
+  CONTENT_EXPORT static void RegisterFactory(AudioDeviceFactory* factory);
+
+  // Unregister the previously registered factory. With no factory registered,
+  // the default AudioRendererSinks will be created.
+  CONTENT_EXPORT static void UnregisterFactory();
+
+ private:
+  // The current globally registered factory. This is NULL when we should
+  // create the default AudioRendererSinks.
+  CONTENT_EXPORT static AudioDeviceFactory* factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioDeviceFactory);
+};
+
+#endif  // CONTENT_RENDERER_MEDIA_AUDIO_DEVICE_FACTORY_H_