Fix race conditions in window snapshot code.

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 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/renderer/gpu/render_widget_compositor.h"
 
 #include <limits>
 #include <string>
 
 #if defined(OS_ANDROID)
@@ skipping 356 matching lines @@
 
 void RenderWidgetCompositor::SetOverdrawBottomHeight(
     float overdraw_bottom_height) {
   layer_tree_host_->SetOverdrawBottomHeight(overdraw_bottom_height);
 }
 
 void RenderWidgetCompositor::SetNeedsRedrawRect(gfx::Rect damage_rect) {
   layer_tree_host_->SetNeedsRedrawRect(damage_rect);
 }
 
+void RenderWidgetCompositor::SetNeedsForcedRedraw() {
+  layer_tree_host_->SetNextCommitForcesRedraw();
+  setNeedsRedraw();
+}
+
 void RenderWidgetCompositor::SetLatencyInfo(
     const ui::LatencyInfo& latency_info) {
   layer_tree_host_->SetLatencyInfo(latency_info);
 }
 
 int RenderWidgetCompositor::GetLayerTreeId() const {
   return layer_tree_host_->id();
 }
 
 void RenderWidgetCompositor::NotifyInputThrottledUntilCommit() {
@@ skipping 234 matching lines @@
   if (!suppress_schedule_composite_)
     widget_->scheduleComposite();
 }
 
 scoped_refptr<cc::ContextProvider>
 RenderWidgetCompositor::OffscreenContextProvider() {
   return RenderThreadImpl::current()->OffscreenCompositorContextProvider();
 }
 
 }  // namespace content