Move audio messages to their own file.

TBR=hclam
Review URL: http://codereview.chromium.org/6717001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@78903 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/ipc/ipc_message_utils.h b/ipc/ipc_message_utils.h
index c2e6a589..6aaa3f3 100644
--- a/ipc/ipc_message_utils.h
+++ b/ipc/ipc_message_utils.h
@@ -80,6 +80,7 @@
   DeviceOrientationMsgStart,
   DesktopNotificationMsgStart,
   GeolocationMsgStart,
+  AudioMsgStart,
   LastIPCMsgStart      // Must come last.
 };