Drop frontbuffers with ui-use-gpu-process, synchronized with browser, decoupled from backbuffer dro…

content/browser/gpu/gpu_process_host_ui_shim.cc

 // 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.
 
 #include "content/browser/gpu/gpu_process_host_ui_shim.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 392 matching lines @@
   if (!view)
     return;
 
   view->AcceleratedSurfaceSuspend();
 }
 
 #if defined(USE_AURA)
 
 void GpuProcessHostUIShim::OnAcceleratedSurfaceRelease(
     const GpuHostMsg_AcceleratedSurfaceRelease_Params& params) {
+  bool success = false;
+
   RenderWidgetHostViewPort* view = GetRenderWidgetHostViewFromSurfaceID(
       params.surface_id);
-  if (!view)
-    return;
-  view->AcceleratedSurfaceRelease(params.identifier);
+  if (view)
+    success = view->AcceleratedSurfaceRelease(params.identifier);
+
+  Send(new AcceleratedSurfaceMsg_ReleaseACK(params.route_id,
+                                            params.identifier,
+                                            success));
 }
 
 #endif