Let PaintAtAck send an int tag instead of the TransportDIB handle.

chrome/common/render_messages_internal.h

 // Copyright (c) 2010 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.
 
 // This header is meant to be included in multiple passes, hence no traditional
 // header guard.
 // See ipc_message_macros.h for explanation of the macros and passes.
 
 #include <map>
 #include <string>
@@ skipping 135 matching lines @@
   // should only result in purging objects we can recalculate, e.g. caches or
   // JS garbage, not in purging irreplaceable objects.
   IPC_MESSAGE_CONTROL0(ViewMsg_PurgeMemory)
 
   // Sent to render the view into the supplied transport DIB, resize
   // the web widget to match the |page_size|, scale it by the
   // appropriate scale to make it fit the |desired_size|, and return
   // it.  In response to this message, the host generates a
   // ViewHostMsg_PaintAtSize_ACK message.  Note that the DIB *must* be
   // the right size to receive an RGBA image at the |desired_size|.
-  IPC_MESSAGE_ROUTED3(ViewMsg_PaintAtSize,
+  IPC_MESSAGE_ROUTED4(ViewMsg_PaintAtSize,
                       TransportDIB::Handle /* dib_handle */,
+                      int /* tag */,

[brettw at google, 2010/07/19 17:45:23]

Can you add to the comment for this message about what tag is and that it will
be sent back with the ACK?

[Nico, 2010/07/19 18:48:30]

Done.

                       gfx::Size /* page_size */,
                       gfx::Size /* desired_size */)
 
   // Tells the render view that a ViewHostMsg_UpdateRect message was processed.
   // This signals the render view that it can send another UpdateRect message.
   IPC_MESSAGE_ROUTED0(ViewMsg_UpdateRect_ACK)
 
   // Replies to creating and updating videos.
   IPC_MESSAGE_ROUTED1(ViewMsg_CreateVideo_ACK,
                       int32 /* video_id */)
@@ skipping 948 matching lines @@
   // Sent when the renderer fails a provisional load with an error.
   IPC_MESSAGE_ROUTED4(ViewHostMsg_DidFailProvisionalLoadWithError,
                       bool /* true if it is the main frame */,
                       int /* error_code */,
                       GURL /* url */,
                       bool /* true if the failure is the result of
                               navigating to a POST again and we're going to
                               show the POST interstitial */ )
 
   // Tells the render view that a ViewHostMsg_PaintAtSize message was
   // processed, and the DIB is ready for use.

[brettw at google, 2010/07/19 17:45:23]

Can you add here where tag comes from?

[Nico, 2010/07/19 18:48:30]

Done.

   IPC_MESSAGE_ROUTED2(ViewHostMsg_PaintAtSize_ACK,
-                      TransportDIB::Handle /* dib_handle */,
+                      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 create, update and destroy video layers.
   IPC_MESSAGE_ROUTED1(ViewHostMsg_CreateVideo,
                       gfx::Size /* size */)
@@ skipping 1369 matching lines @@
   IPC_MESSAGE_CONTROL2(ViewHostMsg_Geolocation_Resume,
                        int /* render_view_id */,
                        int /* bridge_id */)
 
   // Send the tree of accessibility data to the browser, where it's cached
   // in order to respond to OS accessibility queries immediately.
   IPC_MESSAGE_ROUTED1(ViewHostMsg_AccessibilityTree,
                       webkit_glue::WebAccessibility)
 
 IPC_END_MESSAGES(ViewHost)