Support audio output device enumeration and selection in PPAPI

ppapi/proxy/ppapi_messages.h

Index: ppapi/proxy/ppapi_messages.h
diff --git a/ppapi/proxy/ppapi_messages.h b/ppapi/proxy/ppapi_messages.h
index 36d6d8730faee63cfe81dcd6872f1eb1b7c9940f..62eccb8091f1cddc4ad3c6be1ea1bfd5f2ec484a 100644
--- a/ppapi/proxy/ppapi_messages.h
+++ b/ppapi/proxy/ppapi_messages.h
@@ -2250,6 +2250,18 @@ IPC_MESSAGE_CONTROL0(PpapiPluginMsg_AudioInput_OpenReply)
 IPC_MESSAGE_CONTROL1(PpapiHostMsg_AudioInput_StartOrStop, bool /* capture */)
 IPC_MESSAGE_CONTROL0(PpapiHostMsg_AudioInput_Close)
 
+// Audio output.
+IPC_MESSAGE_CONTROL0(PpapiHostMsg_AudioOutput_Create)
+IPC_MESSAGE_CONTROL3(PpapiHostMsg_AudioOutput_Open,
+                     std::string /* device_id */,
+                     PP_AudioSampleRate /* sample_rate */,
+                     uint32_t /* sample_frame_count */)
+// Reply to an Open call. This supplies a socket handle and a shared memory
+// handle. Both handles are passed in the ReplyParams struct.
+IPC_MESSAGE_CONTROL0(PpapiPluginMsg_AudioOutput_OpenReply)
+IPC_MESSAGE_CONTROL1(PpapiHostMsg_AudioOutput_StartOrStop, bool /* playback */)
+IPC_MESSAGE_CONTROL0(PpapiHostMsg_AudioOutput_Close)
+
 // BrowserFont -----------------------------------------------------------------
 
 IPC_MESSAGE_CONTROL0(PpapiHostMsg_BrowserFontSingleton_Create)