[scheduler] Teach scheduler about audio state

content/common/child_process_messages.h

Index: content/common/child_process_messages.h
diff --git a/content/common/child_process_messages.h b/content/common/child_process_messages.h
index a3c48897e71ee98be391e119bc47bc00cbe1073e..a2f48bf39876cee13f5a95a8ef91320ccebed58d 100644
--- a/content/common/child_process_messages.h
+++ b/content/common/child_process_messages.h
@@ -123,6 +123,9 @@ IPC_MESSAGE_CONTROL1(ChildProcessMsg_GetChildNonPersistentHistogramData,
 IPC_MESSAGE_CONTROL1(ChildProcessMsg_SetProcessBackgrounded,
                      bool /* background */)
 
+IPC_MESSAGE_CONTROL1(ChildProcessMsg_SetAudioPlaying,

[Sami, 2016/09/29 13:36:07]

bikeshed: SetProcessAudible would make it a little more obvious that it's *this*
process that is playing audio. I think we use "audible" elsewhere for this
purpose too.

[altimin, 2016/09/29 16:29:42]

Done.

+                     bool /* has_audio_playing */)
+
 // Sent to child processes to tell them to purge and suspend.
 IPC_MESSAGE_CONTROL0(ChildProcessMsg_PurgeAndSuspend)