Ensure alpha channel in backbuffer is correct with DirectComposition.

ui/gl/gl_surface_egl.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/gl/gl_surface_egl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/command_line.h"
@@ skipping 746 matching lines @@
 }
 
 bool NativeViewGLSurfaceEGL::SupportsPostSubBuffer() {
   return supports_post_sub_buffer_;
 }
 
 bool NativeViewGLSurfaceEGL::FlipsVertically() const {
   return flips_vertically_;
 }
 
+bool NativeViewGLSurfaceEGL::BuffersFlipped() const {
+  return g_use_direct_composition;
+}
+
 gfx::SwapResult NativeViewGLSurfaceEGL::PostSubBuffer(int x,
                                                       int y,
                                                       int width,
                                                       int height) {
   DCHECK(supports_post_sub_buffer_);
   if (!CommitAndClearPendingOverlays()) {
     DVLOG(1) << "Failed to commit pending overlay planes.";
     return gfx::SwapResult::SWAP_FAILED;
   }
   if (flips_vertically_) {
@@ skipping 247 matching lines @@
 }
 
 void* SurfacelessEGL::GetShareHandle() {
   return NULL;
 }
 
 SurfacelessEGL::~SurfacelessEGL() {
 }
 
 }  // namespace gfx