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..dbef941bed29eecc343b81372061c0e811137c6b 100644
--- a/media/audio/audio_output_ipc.h
+++ b/media/audio/audio_output_ipc.h
@@ -5,10 +5,13 @@
 #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 {
 
@@ -27,6 +30,17 @@ class MEDIA_EXPORT AudioOutputIPCDelegate {
     kStateLast = kError
   };
 
+  // Result of an audio output device switch operation
+  enum SwitchOutputDeviceResult {
+    kSuccess = 0,
+    kNotFoundError,
+    kSecurityError,
+    kObsoleteError,
+    kNotSupportedError,
+    kOtherError,

[miu, 2015/06/09 19:49:25]

The naming "kOtherError" is vague; and, if you go with my suggestion in ARH, it
isn't actually being used for anything.  So, I suggest removing it.

[Guido Urdaneta, 2015/06/10 09:44:55]

Done. 
The idea was to use kOtherError for other (no pun intended) errors in the next
CL. Will initially use other values instead in those cases, and see how the
review goes.

+    kSwitchOutputDeviceResultLast = kOtherError
+  };
+
   // Called when state of an audio stream has changed.
   virtual void OnStateChanged(State state) = 0;