cc: Introduce BeginFrame sequence numbers and acknowledgements.

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 810 matching lines @@
 IPC_MESSAGE_ROUTED2(ViewHostMsg_UpdateZoomLimits,
                     int /* minimum_percent */,
                     int /* maximum_percent */)
 
 IPC_MESSAGE_ROUTED3(
     ViewHostMsg_SwapCompositorFrame,
     uint32_t /* compositor_frame_sink_id */,
     cc::CompositorFrame /* frame */,
     std::vector<IPC::Message> /* messages_to_deliver_with_frame */)
 
+// Sent if the BeginFrame did not cause a SwapCompositorFrame (e.g. because no
+// updates were required or because it was aborted in the renderer).
+IPC_MESSAGE_ROUTED1(ViewHostMsg_BeginFrameDidNotDraw,
+                    cc::BeginFrameAck /* ack */)
+
 // Send back a string to be recorded by UserMetrics.
 IPC_MESSAGE_CONTROL1(ViewHostMsg_UserMetricsRecordAction,
                      std::string /* action */)
 
 // Notifies the browser of an event occurring in the media pipeline.
 IPC_MESSAGE_CONTROL1(ViewHostMsg_MediaLogEvents,
                      std::vector<media::MediaLogEvent> /* events */)
 
 // Requests to lock the mouse. Will result in a ViewMsg_LockMouse_ACK message
 // being sent back.
@@ skipping 84 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.