Adds AudioDevice factory for all audio clients in Chrome

content/renderer/media/audio_device_factory.cc

+// 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.
+
+#include "content/renderer/media/audio_device_factory.h"
+
+#include "base/logging.h"
+#include "content/renderer/media/audio_device.h"
+
+// static
+AudioDeviceFactory* AudioDeviceFactory::factory_ = NULL;
+
+// static
+media::AudioRendererSink* AudioDeviceFactory::Create() {
+  if (factory_) {
+    return factory_->CreateAudioDevice();
+  }
+  return new AudioDevice();
+}
+
+// static
+void AudioDeviceFactory::RegisterFactory(AudioDeviceFactory* factory) {
+  DCHECK(!factory_) << "Can't register two factories at once.";
+  factory_ = factory;
+}
+
+// static
+void AudioDeviceFactory::UnregisterFactory() {
+  DCHECK(factory_) << "No factory to unregister.";
+  factory_ = NULL;
+}