Adds method to provide custom AudioManager at runtime.

media/audio/audio_manager_factory.h

+// Copyright 2015 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 MEDIA_AUDIO_AUDIO_MANAGER_FACTORY_H_
+#define MEDIA_AUDIO_AUDIO_MANAGER_FACTORY_H_
+
+#include "media/base/media_export.h"
+
+namespace media {
+
+class AudioManager;
+class AudioLogFactory;
+
+// Allows a platform-specific implementation of AudioManager to be provided in
+// place of the default implementation at run-time.
+class MEDIA_EXPORT AudioManagerFactory {
+ public:
+  virtual ~AudioManagerFactory() {}
+
+  // Creates an instance of AudioManager implementation. Caller owns the
+  // returned instance. |audio_log_factory| must outlive the returned instance.
+  virtual AudioManager* CreateInstance(AudioLogFactory* audio_log_factory) = 0;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_AUDIO_MANAGER_FACTORY_H_