Add GrabWindowSnapshotAsync tests

ui/aura/root_window_host_ozone.cc

 // Copyright 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 "ui/aura/root_window_host_ozone.h"
 
 #include "ui/aura/root_window.h"
 #include "ui/events/ozone/event_factory_ozone.h"
 #include "ui/gfx/ozone/surface_factory_ozone.h"
 #include "ui/ozone/ozone_platform.h"
@@ skipping 15 matching lines @@
   widget_ = surface_factory->GetAcceleratedWidget();
 
   surface_factory->AttemptToResizeAcceleratedWidget(widget_, bounds_);
 
   base::MessagePumpOzone::Current()->AddDispatcherForRootWindow(this);
   CreateCompositor(GetAcceleratedWidget());
 }
 
 WindowTreeHostOzone::~WindowTreeHostOzone() {
   base::MessagePumpOzone::Current()->RemoveDispatcherForRootWindow(0);
+  DestroyCompositor();
 }
 
 bool WindowTreeHostOzone::Dispatch(const base::NativeEvent& ne) {
   ui::Event* event = static_cast<ui::Event*>(ne);
   if (event->IsTouchEvent()) {
     ui::TouchEvent* touchev = static_cast<ui::TouchEvent*>(ne);
     delegate_->OnHostTouchEvent(touchev);
   } else if (event->IsKeyEvent()) {
     ui::KeyEvent* keyev = static_cast<ui::KeyEvent*>(ne);
     delegate_->OnHostKeyEvent(keyev);
@@ skipping 79 matching lines @@
   return new WindowTreeHostOzone(bounds);
 }
 
 // static
 gfx::Size WindowTreeHost::GetNativeScreenSize() {
   NOTIMPLEMENTED();
   return gfx::Size();
 }
 
 }  // namespace aura