Add IPC interface for switching the audio output device for a given audio stream in the browser.

media/audio/audio_output_ipc.h

Index: media/audio/audio_output_ipc.h
diff --git a/media/audio/audio_output_ipc.h b/media/audio/audio_output_ipc.h
index f85d8e0195325dfc3add33238bc77d56a9d85cc2..05e4b288d569ed02632fda01193479be85dda43d 100644
--- a/media/audio/audio_output_ipc.h
+++ b/media/audio/audio_output_ipc.h
@@ -5,13 +5,27 @@
 #ifndef MEDIA_AUDIO_AUDIO_OUTPUT_IPC_H_
 #define MEDIA_AUDIO_AUDIO_OUTPUT_IPC_H_
 
+#include <string>
+
 #include "base/memory/shared_memory.h"
 #include "base/sync_socket.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/media_export.h"
+#include "url/gurl.h"
 
 namespace media {
 
+// Result of an audio output device switch operation
+enum SwitchOutputDeviceResult {
+  SWITCH_OUTPUT_DEVICE_RESULT_SUCCESS = 0,
+  SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_FOUND,
+  SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_AUTHORIZED,
+  SWITCH_OUTPUT_DEVICE_RESULT_ERROR_OBSOLETE,
+  SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_SUPPORTED,
+  SWITCH_OUTPUT_DEVICE_RESULT_LAST =
+      SWITCH_OUTPUT_DEVICE_RESULT_ERROR_NOT_SUPPORTED,
+};
+
 // Contains IPC notifications for the state of the server side
 // (AudioOutputController) audio state changes and when an AudioOutputController
 // has been created.  Implemented by AudioOutputDevice.