Simplify the logic in DesktopWindowTreeHostX11 for FocusOut

ui/aura/window_event_dispatcher.cc

 // Copyright 2014 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 "ui/aura/window_event_dispatcher.h"
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 183 matching lines @@
 
 gfx::Point WindowEventDispatcher::GetLastMouseLocationInRoot() const {
   gfx::Point location = Env::GetInstance()->last_mouse_location();
   client::ScreenPositionClient* client =
       client::GetScreenPositionClient(window());
   if (client)
     client->ConvertPointFromScreen(window(), &location);
   return location;
 }
 
-void WindowEventDispatcher::OnHostLostMouseGrab() {
-  mouse_pressed_handler_ = NULL;
-  mouse_moved_handler_ = NULL;
-}
-
 void WindowEventDispatcher::OnCursorMovedToRootLocation(
     const gfx::Point& root_location) {
   SetLastMouseLocation(window(), root_location);
   synthesize_mouse_move_ = false;
 }
 
 void WindowEventDispatcher::OnPostNotifiedWindowDestroying(Window* window) {
   OnWindowHidden(window, WINDOW_DESTROYED);
 }
 
@@ skipping 644 matching lines @@
       break;
 
     default:
       NOTREACHED();
       break;
   }
   PreDispatchLocatedEvent(target, event);
 }
 
 }  // namespace aura