ObserverList::HasObserver now takes a const pointer.

ui/aura/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_WINDOW_H_
 #define UI_AURA_WINDOW_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 205 matching lines @@
 
   // Moves the cursor to the specified location relative to the window.
   void MoveCursorTo(const gfx::Point& point_in_window);
 
   // Returns the cursor for the specified point, in window coordinates.
   gfx::NativeCursor GetCursor(const gfx::Point& point) const;
 
   // Add/remove observer.
   void AddObserver(WindowObserver* observer);
   void RemoveObserver(WindowObserver* observer);
-  bool HasObserver(WindowObserver* observer);
+  bool HasObserver(const WindowObserver* observer) const;
 
   void set_ignore_events(bool ignore_events) { ignore_events_ = ignore_events; }
   bool ignore_events() const { return ignore_events_; }
 
   // Sets the window to grab hits for an area extending |insets| pixels inside
   // its bounds (even if that inner region overlaps a child window). This can be
   // used to create an invisible non-client area that overlaps the client area.
   void set_hit_test_bounds_override_inner(const gfx::Insets& insets) {
     hit_test_bounds_override_inner_ = insets;
   }
@@ skipping 300 matching lines @@
   };
 
   std::map<const void*, Value> prop_map_;
 
   DISALLOW_COPY_AND_ASSIGN(Window);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_WINDOW_H_