Add a lock screen example.

ui/aura/window.h

 // Copyright (c) 2011 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_WINDOW_H_
 #define UI_AURA_WINDOW_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 102 matching lines @@
   void SetEventFilter(EventFilter* event_filter);
 
   // Handles a mouse event. Returns true if handled.
   bool OnMouseEvent(MouseEvent* event);
 
   // Handles a key event. Returns true if handled.
   bool OnKeyEvent(KeyEvent* event);
 
   WindowDelegate* delegate() { return delegate_; }
 
+  // When set to true, this Window will consume all events targeted at it or
+  // Windows below it in the z-order, but only if this Window has children. This
+  // is used to implement lock-screen type functionality where we do not want
+  // events to be sent to running logged-in windows when the lock screen is
+  // displayed.
+  void set_consumes_events(bool consumes_events) {
+    consumes_events_ = consumes_events;
+  }
+
   // Returns true if the mouse pointer at the specified |point| can trigger an
   // event for this Window.
   // TODO(beng):
   // A Window can supply a hit-test mask to cause some portions of itself to not
   // trigger events, causing the events to fall through to the Window behind.
   bool HitTest(const gfx::Point& point);
 
   // Returns the Window that most closely encloses |point| for the purposes of
   // event targeting.
   Window* GetEventHandlerForPoint(const gfx::Point& point);
@@ skipping 49 matching lines @@
   Windows children_;
 
   int id_;
   std::string name_;
 
   scoped_ptr<EventFilter> event_filter_;
   scoped_ptr<LayoutManager> layout_manager_;
 
   void* user_data_;
 
+  // When true, events are not sent to windows behind this one in the z-order,
+  // provided this window has children. See set_consumes_events().
+  bool consumes_events_;
+
   DISALLOW_COPY_AND_ASSIGN(Window);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_WINDOW_H_