Don't dispatch event after shutdown on AshWTHUnified

ash/display/mirror_window_controller.cc

 // Copyright (c) 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 "ash/display/mirror_window_controller.h"
 
 #if defined(USE_X11)
 #include <X11/Xlib.h>
 #include <X11/extensions/XInput2.h>
 
@@ skipping 127 matching lines @@
       aura::client::SetCaptureClient(host->window(), new NoneCaptureClient());
       host->Show();
 
       aura::Window* mirror_window = host_info->mirror_window =
           new aura::Window(nullptr);
       mirror_window->Init(ui::LAYER_SOLID_COLOR);
       host->window()->AddChild(mirror_window);
       mirror_window->SetBounds(host->window()->bounds());
       mirror_window->Show();
       if (reflector_) {
-        // TODO(oshima): Enable this once reflect change is landed.
+        // TODO(oshima): Enable this once reflector change is landed.
         // reflector_->AddMirroringLayer(mirror_window->layer());
       } else {
         reflector_ =
             aura::Env::GetInstance()->context_factory()->CreateReflector(
                 Shell::GetPrimaryRootWindow()->GetHost()->compositor(),
                 mirror_window->layer());
       }
     } else {
       aura::WindowTreeHost* host = mirroring_host_info_map_[display_info.id()]
                                        ->ash_host->AsWindowTreeHost();
@@ skipping 101 matching lines @@
 
 void MirrorWindowController::CloseAndDeleteHost(MirroringHostInfo* host_info) {
   aura::WindowTreeHost* host = host_info->ash_host->AsWindowTreeHost();
   NoneCaptureClient* capture_client = static_cast<NoneCaptureClient*>(
       aura::client::GetCaptureClient(host->window()));
   aura::client::SetCaptureClient(host->window(), NULL);
   delete capture_client;
 
   host->RemoveObserver(Shell::GetInstance()->display_controller());
   host->RemoveObserver(this);
-  // reflector_->RemoveMirroringLayer(host_info->mirror_window->layer());
+  host_info->ash_host->PrepareForShutdown();
+  // TODO(oshima): Enable this once reflector change is landed.
+  // reflector_->RemovedMirroringLayer(mirror_window->layer());
   delete host_info;
 }
 
 scoped_ptr<RootWindowTransformer>
 MirrorWindowController::CreateRootWindowTransformer() const {
   DisplayManager* display_manager = Shell::GetInstance()->display_manager();
   const DisplayInfo& mirror_display_info =
       display_manager->GetDisplayInfo(display_manager->mirroring_display_id());
   const DisplayInfo& source_display_info = display_manager->GetDisplayInfo(
       Shell::GetScreen()->GetPrimaryDisplay().id());
   DCHECK(display_manager->IsInMirrorMode());
   return scoped_ptr<RootWindowTransformer>(
       CreateRootWindowTransformerForMirroredDisplay(source_display_info,
                                                     mirror_display_info));
 }
 
 }  // namespace ash