[scheduler] Teach scheduler about audio state

content/common/child_process_messages.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Common IPC messages used for child processes.
 // Multiply-included message file, hence no include guard.
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 105 matching lines @@
                      int /* shm_size */)
 
 // Send to all the child processes to send back histogram data.
 IPC_MESSAGE_CONTROL1(ChildProcessMsg_GetChildNonPersistentHistogramData,
                      int /* sequence_number */)
 
 // Sent to child processes to tell them to enter or leave background mode.
 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)
 
 ////////////////////////////////////////////////////////////////////////////////
 // Messages sent from the child process to the browser.
 
 // A renderer sends this when it wants to create a connection to the GPU
 // process. The browser will create the GPU process if necessary, and will
 // return a handle to the channel via a GpuChannelEstablished message.
 IPC_SYNC_MESSAGE_CONTROL0_3(ChildProcessHostMsg_EstablishGpuChannel,
@@ skipping 84 matching lines @@
 // memory.
 IPC_MESSAGE_CONTROL1(ChildProcessHostMsg_DeletedDiscardableSharedMemory,
                      content::DiscardableSharedMemoryId)
 
 #if defined(OS_LINUX)
 // Asks the browser to change the priority of thread.
 IPC_MESSAGE_CONTROL2(ChildProcessHostMsg_SetThreadPriority,
                      base::PlatformThreadId,
                      base::ThreadPriority)
 #endif