Fix AshWindowTreeHost shutdown for Ozone X11.

ash/host/ash_window_tree_host_platform.cc

 // Copyright 2016 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 "ash/host/ash_window_tree_host_platform.h"
 
 #include <utility>
 
 #include "ash/host/root_window_transformer.h"
 #include "ash/host/transformer_helper.h"
@@ skipping 57 matching lines @@
   return this;
 }
 
 void AshWindowTreeHostPlatform::PrepareForShutdown() {
   // Block the root window from dispatching events because it is weird for a
   // ScreenPositionClient not to be attached to the root window and for
   // ui::EventHandlers to be unable to convert the event's location to screen
   // coordinates.
   window()->SetEventTargeter(
       std::unique_ptr<ui::EventTargeter>(new ui::NullEventTargeter));
+
+  // Do anything platform specific necessary before shutdown (eg. stop
+  // listening for configuration XEvents).
+  platform_window()->PrepareForShutdown();
 }
 
 void AshWindowTreeHostPlatform::SetRootTransform(
     const gfx::Transform& transform) {
   transformer_helper_.SetTransform(transform);
 }
 
 gfx::Transform AshWindowTreeHostPlatform::GetRootTransform() const {
   return transformer_helper_.GetTransform();
 }
@@ skipping 37 matching lines @@
 #if defined(USE_OZONE)
   DCHECK(ui::OzonePlatform::GetInstance()->GetInputController());
 
   // Temporarily pause tap-to-click when the cursor is hidden.
   ui::OzonePlatform::GetInstance()->GetInputController()->SetTapToClickPaused(
       state);
 #endif
 }
 
 }  // namespace ash