Adds method to provide custom AudioManager at runtime.

media/audio/audio_manager.h

Index: media/audio/audio_manager.h
diff --git a/media/audio/audio_manager.h b/media/audio/audio_manager.h
index 5e49b8b399afd138c35f659d73823be06a0e9567..5da521dcca33de4e76b0006cf64fefa39940bca0 100644
--- a/media/audio/audio_manager.h
+++ b/media/audio/audio_manager.h
@@ -21,13 +21,24 @@ class SingleThreadTaskRunner;
 namespace media {
 
 class AudioInputStream;
+class AudioManagerFactory;
 class AudioOutputStream;
 
 // Manages all audio resources.  Provides some convenience functions that avoid
 // the need to provide iterators over the existing streams.
 class MEDIA_EXPORT AudioManager {
-  public:
-   virtual ~AudioManager();
+ public:
+  virtual ~AudioManager();
+
+  // This provides an alternative to the statically linked factory method used
+  // to create AudioManager. This is useful for dynamically-linked third
+  // party clients seeking to provide a platform-specific implementation of
+  // AudioManager. After this is called, all static AudioManager::Create*
+  // methods will return an instance of AudioManager provided by |factory|. This
+  // call may be made at most once per process, and before any calls to static
+  // AudioManager::Create* methods. This method takes ownership of |factory|,
+  // which must not be NULL.
+  static void SetFactory(AudioManagerFactory* factory);
 
   // Construct the audio manager; only one instance is allowed.  The manager
   // will forward CreateAudioLog() calls to the provided AudioLogFactory; as
@@ -44,6 +55,10 @@ class MEDIA_EXPORT AudioManager {
   // Similar to Create() except uses a FakeAudioLogFactory for testing.
   static AudioManager* CreateForTesting();
 
+  // Should only be used for testing. Resets a previously-set
+  // AudioManagerFactory. The instance of AudioManager is not affected.
+  static void ResetFactoryForTesting();
+
   // Returns the pointer to the last created instance, or NULL if not yet
   // created. This is a utility method for the code outside of media directory,
   // like src/chrome.
@@ -130,7 +145,8 @@ class MEDIA_EXPORT AudioManager {
   // Do not free the returned AudioInputStream. It is owned by AudioManager.
   // When you are done with it, call |Stop()| and |Close()| to release it.
   virtual AudioInputStream* MakeAudioInputStream(
-      const AudioParameters& params, const std::string& device_id) = 0;
+      const AudioParameters& params,
+      const std::string& device_id) = 0;
 
   // Returns the task runner used for audio IO.
   virtual scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner() = 0;