Fix "modal isn't modal in multi displays" issue

ash/wm/event_client_impl.cc

 // Copyright (c) 2012 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/wm/event_client_impl.h"
 
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/shell_window_ids.h"
 #include "ash/shell.h"
 #include "ui/aura/window.h"
 #include "ui/keyboard/keyboard_util.h"
 
 namespace ash {
 
 EventClientImpl::EventClientImpl() {
 }
 
 EventClientImpl::~EventClientImpl() {
 }
 
 bool EventClientImpl::CanProcessEventsWithinSubtree(
     const aura::Window* window) const {
+  // TODO(oshima): Migrate this logic to Shell::CanWindowReceieveEvents and
+  // remove this.
   const aura::Window* root_window = window ? window->GetRootWindow() : NULL;
   if (!root_window ||
       !Shell::GetInstance()->session_state_delegate()->IsUserSessionBlocked()) {
     return true;
   }
 
   const aura::Window* lock_screen_containers = Shell::GetContainer(
       root_window,
       kShellWindowId_LockScreenContainersContainer);
   const aura::Window* lock_background_containers = Shell::GetContainer(
@@ skipping 16 matching lines @@
                            virtual_keyboard_container->Contains(window));
   }
   return can_process_events;
 }
 
 ui::EventTarget* EventClientImpl::GetToplevelEventTarget() {
   return Shell::GetInstance();
 }
 
 }  // namespace ash