Delay UpdateRect until the SwapBuffers callback when accelerated compositing is on.

content/common/view_messages.h

 // Copyright (c) 2011 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 "base/process.h"
 #include "base/shared_memory.h"
 #include "content/common/content_export.h"
@@ skipping 500 matching lines @@
   //     Indicates that this is a response to a ViewMsg_WasRestored message.
   //
   //   ViewHostMsg_UpdateRect_Flags::IS_REPAINT_ACK
   //     Indicates that this is a response to a ViewMsg_Repaint message.
   //
   // If flags is zero, then this message corresponds to an unsolicited paint
   // request by the render view.  Any of the above bits may be set in flags,
   // which would indicate that this paint message is an ACK for multiple
   // request messages.
   IPC_STRUCT_MEMBER(int, flags)
+
+  // Whether or not the renderer expects a ViewMsg_UpdateRect_ACK for this
+  // update. True for 2D painting, but false for accelerated compositing.
+  IPC_STRUCT_MEMBER(bool, needs_ack)
 IPC_STRUCT_END()
 
 IPC_STRUCT_BEGIN(ViewHostMsg_DidFailProvisionalLoadWithError_Params)
   // The frame ID for the failure report.
   IPC_STRUCT_MEMBER(int64, frame_id)
   // True if this is the top-most frame.
   IPC_STRUCT_MEMBER(bool, is_main_frame)
   // Error code as reported in the DidFailProvisionalLoad callback.
   IPC_STRUCT_MEMBER(int, error_code)
   // An error message generated from the error_code. This can be an empty
@@ skipping 889 matching lines @@
 // the tag sent along with ViewMsg_PaintAtSize.
 IPC_MESSAGE_ROUTED2(ViewHostMsg_PaintAtSize_ACK,
                     int /* tag */,
                     gfx::Size /* size */)
 
 // Sent to update part of the view.  In response to this message, the host
 // generates a ViewMsg_UpdateRect_ACK message.
 IPC_MESSAGE_ROUTED1(ViewHostMsg_UpdateRect,
                     ViewHostMsg_UpdateRect_Params)
 
+// Sent to unblock the browser's UI thread if it is waiting on an UpdateRect,
+// which may get delayed until the browser's UI unblocks.
+IPC_MESSAGE_ROUTED0(ViewHostMsg_UpdateIsDelayed)
+
 // Sent by the renderer when accelerated compositing is enabled or disabled to
 // notify the browser whether or not is should do painting.
 IPC_MESSAGE_ROUTED1(ViewHostMsg_DidActivateAcceleratedCompositing,
                     bool /* true if the accelerated compositor is actve */)
 
 // Acknowledges receipt of a ViewMsg_HandleInputEvent message.
 IPC_MESSAGE_ROUTED2(ViewHostMsg_HandleInputEvent_ACK,
                     WebKit::WebInputEvent::Type,
                     bool /* processed */)
 
@@ skipping 510 matching lines @@
                      media::MediaLogEvent /* event */)
 
 // Requests to lock the mouse. Will result in a ViewMsg_LockMouse_ACK message
 // being sent back.
 IPC_MESSAGE_ROUTED0(ViewHostMsg_LockMouse)
 
 // Requests to unlock the mouse. A ViewMsg_MouseLockLost message will be sent
 // whenever the mouse is unlocked (which may or may not be caused by
 // ViewHostMsg_UnlockMouse).
 IPC_MESSAGE_ROUTED0(ViewHostMsg_UnlockMouse)