Add GrabWindowSnapshotAsync tests

ui/aura/root_window_host_x11.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/aura/root_window_host_x11.h"
 
 #include <strings.h>
 #include <X11/cursorfont.h>
 #include <X11/extensions/Xfixes.h>
 #include <X11/extensions/XInput2.h>
@@ skipping 371 matching lines @@
   CreateCompositor(GetAcceleratedWidget());
 }
 
 WindowTreeHostX11::~WindowTreeHostX11() {
   Env::GetInstance()->RemoveObserver(this);
   base::MessagePumpX11::Current()->RemoveDispatcherForRootWindow(this);
   base::MessagePumpX11::Current()->RemoveDispatcherForWindow(xwindow_);
 
   UnConfineCursor();
 
+  DestroyCompositor();
   XDestroyWindow(xdisplay_, xwindow_);
 }
 
 bool WindowTreeHostX11::Dispatch(const base::NativeEvent& event) {
   XEvent* xev = event;
 
   if (FindEventTarget(event) == x_root_window_)
     return DispatchEventForRootWindow(event);
 
   switch (xev->type) {
@@ skipping 650 matching lines @@
 }
 
 namespace test {
 
 void SetUseOverrideRedirectWindowByDefault(bool override_redirect) {
   default_override_redirect = override_redirect;
 }
 
 }  // namespace test
 }  // namespace aura