[scheduler] Teach scheduler about audio state

content/common/frame_messages.h

 // Copyright 2013 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 interacting with frames.
 // Multiply-included message file, hence no include guard.
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 900 matching lines @@
 // only be sent to the main frame.
 IPC_MESSAGE_ROUTED0(FrameMsg_EnableViewSourceMode)
 
 // Tells the frame to suppress any further modal dialogs. This ensures that no
 // ScopedPageLoadDeferrer is on the stack for SwapOut.
 IPC_MESSAGE_ROUTED0(FrameMsg_SuppressFurtherDialogs)
 
 IPC_MESSAGE_ROUTED1(FrameMsg_RunFileChooserResponse,
                     std::vector<content::FileChooserFileInfo>)
 
+IPC_MESSAGE_ROUTED1(FrameMsg_AudioStateChanged, bool /* is_audio_playing */)
+
 // -----------------------------------------------------------------------------
 // Messages sent from the renderer to the browser.
 
 // Blink and JavaScript error messages to log to the console
 // or debugger UI.
 IPC_MESSAGE_ROUTED4(FrameHostMsg_AddMessageToConsole,
                     int32_t,        /* log level */
                     base::string16, /* msg */
                     int32_t,        /* line number */
                     base::string16 /* source id */)
@@ skipping 569 matching lines @@
 // nearest find result in the sending frame.
 IPC_MESSAGE_ROUTED2(FrameHostMsg_GetNearestFindResult_Reply,
                     int /* nfr_request_id */,
                     float /* distance */)
 #endif
 
 // Adding a new message? Stick to the sort order above: first platform
 // independent FrameMsg, then ifdefs for platform specific FrameMsg, then
 // platform independent FrameHostMsg, then ifdefs for platform specific
 // FrameHostMsg.