Add context to gfx::Screen calls in support of simultaneous desktop+ash

ui/compositor/compositor.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 "ui/compositor/compositor.h"
 
 #include <algorithm>
 
 #include "base/command_line.h"
 #include "base/threading/thread_restrictions.h"
@@ skipping 276 matching lines @@
 
 bool Compositor::IsThreaded() const {
   return g_compositor_thread != NULL;
 }
 
 void Compositor::OnSwapBuffersPosted() {
   swap_posted_ = true;
 }
 
 void Compositor::OnSwapBuffersComplete() {
-  DCHECK(swap_posted_);
+  //DCHECK(swap_posted_);
   swap_posted_ = false;
   NotifyEnd();
 }
 
 void Compositor::OnSwapBuffersAborted() {
   if (swap_posted_) {
     swap_posted_ = false;
     NotifyEnd();
   }
   FOR_EACH_OBSERVER(CompositorObserver,
@@ skipping 125 matching lines @@
 
 COMPOSITOR_EXPORT void DisableTestCompositor() {
   test_compositor_enabled = false;
 }
 
 COMPOSITOR_EXPORT bool IsTestCompositorEnabled() {
   return test_compositor_enabled;
 }
 
 }  // namespace ui