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

content/browser/renderer_host/render_widget_host_view_aura.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/renderer_host/render_widget_host_view_aura.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/weak_ptr.h"
 #include "content/browser/renderer_host/backing_store_skia.h"
@@ skipping 539 matching lines @@
         gfx::Size(width, height), surface_handle));
   if (!surface) {
     LOG(ERROR) << "Failed to create ImageTransportClient";
     return;
   }
   *shm_handle = surface->Handle();
 
   image_transport_clients_[*surface_handle] = surface;
 }
 
-void RenderWidgetHostViewAura::AcceleratedSurfaceRelease(
+bool RenderWidgetHostViewAura::AcceleratedSurfaceRelease(
     uint64 surface_handle) {
+  if (host_->IsVisible() && current_surface_ == surface_handle)
+    return false;
   if (current_surface_ == surface_handle) {
     current_surface_ = 0;
     UpdateExternalTexture();
   }
   image_transport_clients_.erase(surface_handle);
+  return true;
 }
 
 void RenderWidgetHostViewAura::SetBackground(const SkBitmap& background) {
   content::RenderWidgetHostViewBase::SetBackground(background);
   host_->SetBackground(background);
   window_->layer()->SetFillsBoundsOpaquely(background.isOpaque());
 }
 
 bool RenderWidgetHostViewAura::CopyFromCompositingSurface(
       const gfx::Size& size,
@@ skipping 675 matching lines @@
     WebKit::WebScreenInfo* results) {
   const gfx::Size size = gfx::Screen::GetPrimaryMonitorSize();
   results->rect = WebKit::WebRect(0, 0, size.width(), size.height());
   results->availableRect = results->rect;
   // TODO(derat): Don't hardcode this?
   results->depth = 24;
   results->depthPerComponent = 8;
   results->verticalDPI = 96;
   results->horizontalDPI = 96;
 }