Register a separate default ui::EventTarget for Aura (Ash) to ensure that it does not interfere wit…

ash/shell.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/shell.h"
 
 #include <algorithm>
 #include <string>
 
 #include "ash/accelerators/focus_manager_factory.h"
@@ skipping 491 matching lines @@
   AddShellObserver(session_state_controller_.get());
 
   if (initially_hide_cursor_)
     cursor_manager_.ShowCursor(false);
 
   // Cursor might have been hidden by somethign other than chrome.
   // Let the first mouse event show the cursor.
   env_filter_->set_cursor_hidden_by_filter(true);
 }
 
+bool Shell::CanAcceptEvents() {
+  return true;
+}
+
+ui::EventTarget* Shell::GetParentTarget() {
+  return NULL;
+}
+
 void Shell::AddEnvEventFilter(aura::EventFilter* filter) {
-  aura::Env::GetInstance()->AddPreTargetHandler(filter);
+  AddPreTargetHandler(filter);
 }
 
 void Shell::RemoveEnvEventFilter(aura::EventFilter* filter) {
-  aura::Env::GetInstance()->RemovePreTargetHandler(filter);
+  RemovePreTargetHandler(filter);
 }
 
 void Shell::ShowContextMenu(const gfx::Point& location_in_screen) {
   // No context menus if user have not logged in.
   if (!delegate_.get() || !delegate_->IsUserLoggedIn())
     return;
   // No context menus when screen is locked.
   if (IsScreenLocked())
     return;
 
@@ skipping 268 matching lines @@
        iter != controllers.end(); ++iter) {
     if ((*iter)->GetSystemModalLayoutManager(window)->
             CanWindowReceiveEvents(window)) {
       return true;
     }
   }
   return false;
 }
 
 }  // namespace ash