aura: Support releasing the OutputSurface()

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 <deque>
 
 #include "base/bind.h"
@@ skipping 289 matching lines @@
 
 void Compositor::SetAcceleratedWidget(gfx::AcceleratedWidget widget) {
   // This function should only get called once.
   DCHECK(!widget_valid_);
   widget_ = widget;
   widget_valid_ = true;
   if (output_surface_requested_)
     context_factory_->CreateOutputSurface(weak_ptr_factory_.GetWeakPtr());
 }
 
+gfx::AcceleratedWidget Compositor::ReleaseAcceleratedWidget() {
+  DCHECK(!IsVisible());
+  if (!host_->output_surface_lost())
+    host_->ReleaseOutputSurface();
+  context_factory_->RemoveCompositor(this);
+  widget_valid_ = false;
+  gfx::AcceleratedWidget widget = widget_;
+  widget_ = gfx::kNullAcceleratedWidget;
+  return widget;
+}
+
 gfx::AcceleratedWidget Compositor::widget() const {
   DCHECK(widget_valid_);
   return widget_;
 }
 
 scoped_refptr<CompositorVSyncManager> Compositor::vsync_manager() const {
   return vsync_manager_;
 }
 
 void Compositor::AddObserver(CompositorObserver* observer) {
@@ skipping 156 matching lines @@
                     observer_list_,
                     OnCompositingLockStateChanged(this));
 }
 
 void Compositor::CancelCompositorLock() {
   if (compositor_lock_)
     compositor_lock_->CancelLock();
 }
 
 }  // namespace ui