Don't activate a window if screen is locked.

ui/aura/root_window.h

 // 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.
 
 #ifndef UI_AURA_ROOT_WINDOW_H_
 #define UI_AURA_ROOT_WINDOW_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
@@ skipping 141 matching lines @@
   // Called whenever the mouse moves, tracks the current |mouse_moved_handler_|,
   // sending exited and entered events as its value changes.
   void HandleMouseMoved(const MouseEvent& event, Window* target);
 
   bool ProcessMouseEvent(Window* target, MouseEvent* event);
   bool ProcessKeyEvent(Window* target, KeyEvent* event);
   ui::TouchStatus ProcessTouchEvent(Window* target, TouchEvent* event);
 
   // Overridden from Window:
   virtual bool CanFocus() const OVERRIDE;
+  virtual bool CanReceiveEvents() const OVERRIDE;
   virtual internal::FocusManager* GetFocusManager() OVERRIDE;
   virtual RootWindow* GetRootWindow() OVERRIDE;
   virtual void WindowDetachedFromRootWindow(Window* window) OVERRIDE;
 
   // Overridden from ui::LayerAnimationObserver:
   virtual void OnLayerAnimationEnded(
       const ui::LayerAnimationSequence* animation) OVERRIDE;
   virtual void OnLayerAnimationScheduled(
       const ui::LayerAnimationSequence* animation) OVERRIDE;
   virtual void OnLayerAnimationAborted(
@@ skipping 46 matching lines @@
   Window* mouse_moved_handler_;
   Window* focused_window_;
   Window* touch_event_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(RootWindow);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ROOT_WINDOW_H_