arc: Fix crash on window close (on close race condition).

chrome/browser/ui/ash/launcher/arc_app_window_launcher_controller.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 "chrome/browser/ui/ash/launcher/arc_app_window_launcher_controller.h"
 
 #include <string>
 
 #include "ash/common/wm/window_state.h"
 #include "ash/common/wm_shell.h"
 #include "ash/display/display_manager.h"
@@ skipping 320 matching lines @@
 }
 
 void ArcAppWindowLauncherController::OnWindowDestroying(aura::Window* window) {
   auto it =
       std::find(observed_windows_.begin(), observed_windows_.end(), window);
   DCHECK(it != observed_windows_.end());
   observed_windows_.erase(it);
   window->RemoveObserver(this);
 
   for (auto& it : task_id_to_app_window_) {
-    if (it.second->widget() == views::Widget::GetWidgetForNativeWindow(window))
-      it.second->set_widget(nullptr);
+    if (it.second->GetNativeWindow() == window) {
+      OnTaskDestroyed(it.second->task_id());
+      break;
+    }
   }
 }
 
 ArcAppWindowLauncherController::AppWindow*
 ArcAppWindowLauncherController::GetAppWindowForTask(int task_id) {
   TaskIdToAppWindow::iterator it = task_id_to_app_window_.find(task_id);
   if (it == task_id_to_app_window_.end())
     return nullptr;
   return it->second.get();
 }
@@ skipping 279 matching lines @@
 
   if (orientation_lock == arc::mojom::OrientationLock::CURRENT) {
     // Resolve the orientation when it first resolved.
     orientation_lock = GetCurrentOrientation();
     app_window->set_requested_orientation_lock(orientation_lock);
   }
 
   shell->screen_orientation_controller()->LockOrientationForWindow(
       window, BlinkOrientationLockFromMojom(orientation_lock));
 }