Fix AshWindowTreeHost shutdown for Ozone X11.

ui/platform_window/x11/x11_window.cc

 // Copyright 2014 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/platform_window/x11/x11_window.h"
 
 #include <X11/extensions/XInput2.h>
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 
 #include "ui/events/devices/x11/touch_factory_x11.h"
 #include "ui/events/event.h"
 #include "ui/events/event_utils.h"
 #include "ui/events/platform/platform_event_source.h"
 #include "ui/events/platform/x11/x11_event_source.h"
 #include "ui/platform_window/platform_window_delegate.h"
 
 namespace ui {
 
 X11Window::X11Window(PlatformWindowDelegate* delegate, const gfx::Rect& bounds)
     : X11WindowBase(delegate, bounds) {
   DCHECK(PlatformEventSource::GetInstance());
   PlatformEventSource::GetInstance()->AddPlatformEventDispatcher(this);
 }
 
 X11Window::~X11Window() {
+  X11Window::PrepareForShutdown();
+}
+
+void X11Window::PrepareForShutdown() {
   PlatformEventSource::GetInstance()->RemovePlatformEventDispatcher(this);
 }
 
 void X11Window::SetCursor(PlatformCursor cursor) {
   XDefineCursor(xdisplay(), xwindow(), cursor);
 }
 
 void X11Window::ProcessXInput2Event(XEvent* xev) {
   if (!TouchFactory::GetInstance()->ShouldProcessXI2Event(xev))
     return;
@@ skipping 101 matching lines @@
 
     case GenericEvent: {
       ProcessXInput2Event(xev);
       break;
     }
   }
   return POST_DISPATCH_STOP_PROPAGATION;
 }
 
 }  // namespace ui