[scheduler] Teach scheduler about audio state

content/common/view_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.
 
 // IPC messages for page rendering.
 // Multiply-included message file, hence no include guard.
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 652 matching lines @@
 IPC_MESSAGE_ROUTED1(ViewMsg_SetBeginFramePaused, bool /* paused */)
 
 // Sent by the browser when the renderer should generate a new frame.
 IPC_MESSAGE_ROUTED1(ViewMsg_BeginFrame,
                     cc::BeginFrameArgs /* args */)
 
 // Sent by the browser to deliver a compositor proto to the renderer.
 IPC_MESSAGE_ROUTED1(ViewMsg_HandleCompositorProto,
                     std::vector<uint8_t> /* proto */)
 
+// Sent by the browser when the page is starting or stopping to play audio.
+IPC_MESSAGE_ROUTED1(ViewMsg_AudioStateChanged, bool /* is_audio_playing */)
+
 // -----------------------------------------------------------------------------
 // Messages sent from the renderer to the browser.
 
 // Sent by renderer to request a ViewMsg_BeginFrame message for upcoming
 // display events. If |enabled| is true, the BeginFrame message will continue
 // to be be delivered until the notification is disabled.
 IPC_MESSAGE_ROUTED1(ViewHostMsg_SetNeedsBeginFrames,
                     bool /* enabled */)
 
 // Similar to ViewHostMsg_CreateWindow, except used for sub-widgets, like
@@ skipping 320 matching lines @@
                     int /* y */)
 
 #elif defined(OS_MACOSX)
 // Receives content of a web page as plain text.
 IPC_MESSAGE_ROUTED1(ViewMsg_GetRenderedTextCompleted, std::string)
 #endif
 
 // Adding a new message? Stick to the sort order above: first platform
 // independent ViewMsg, then ifdefs for platform specific ViewMsg, then platform
 // independent ViewHostMsg, then ifdefs for platform specific ViewHostMsg.