arc: Fix regression in handling ARC shelf item.

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/shelf/shelf_delegate.h"
 #include "ash/common/wm/maximize_mode/maximize_mode_controller.h"
 #include "ash/common/wm/window_state.h"
@@ skipping 548 matching lines @@
           ->maximize_mode_controller()
           ->IsMaximizeModeWindowManagerEnabled()) {
     AppWindow* app_window = info->app_window();
     if (app_window)
       SetOrientationLockForAppWindow(app_window);
   }
 }
 
 AppWindowLauncherItemController*
 ArcAppWindowLauncherController::ControllerForWindow(aura::Window* window) {
+  if (!window)
+    return nullptr;
+
   AppWindow* app_window = GetAppWindowForTask(active_task_id_);
   if (app_window &&
       app_window->widget() == views::Widget::GetWidgetForNativeWindow(window)) {
     return app_window->controller();
   }
 
   for (auto& it : task_id_to_app_window_info_) {
     AppWindow* app_window = it.second->app_window();
     if (app_window &&
         app_window->widget() ==
             views::Widget::GetWidgetForNativeWindow(window)) {
       return it.second->app_window()->controller();
     }
   }
 
   return nullptr;
 }
 
 void ArcAppWindowLauncherController::OnWindowActivated(
     aura::client::ActivationChangeObserver::ActivationReason reason,
     aura::Window* gained_active,
     aura::Window* lost_active) {
+  AppWindowLauncherController::OnWindowActivated(reason, gained_active,

[khmel, 2017/03/22 00:07:03]

Required to store last active window.

+                                                 lost_active);
   OnTaskSetActive(active_task_id_);
 }
 
 void ArcAppWindowLauncherController::OnMaximizeModeStarted() {
   for (auto& it : task_id_to_app_window_info_) {
     AppWindow* app_window = it.second->app_window();
     if (app_window)
       SetOrientationLockForAppWindow(app_window);
   }
 }
@@ skipping 117 matching lines @@
   const std::string arc_app_id = exo::ShellSurface::GetApplicationId(window);
   if (arc_app_id.empty())
     return -1;
 
   int task_id = -1;
   if (sscanf(arc_app_id.c_str(), "org.chromium.arc.%d", &task_id) != 1)
     return -1;
 
   return task_id;
 }