ObserverList::HasObserver now takes a const pointer.

ui/compositor/compositor.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_COMPOSITOR_COMPOSITOR_H_
 #define UI_COMPOSITOR_COMPOSITOR_H_
 
 #include <string>
 
 #include "base/containers/hash_tables.h"
@@ skipping 198 matching lines @@
   // Returns the main thread task runner this compositor uses. Users of the
   // compositor generally shouldn't use this.
   scoped_refptr<base::SingleThreadTaskRunner> task_runner() const {
     return task_runner_;
   }
 
   // Compositor does not own observers. It is the responsibility of the
   // observer to remove itself when it is done observing.
   void AddObserver(CompositorObserver* observer);
   void RemoveObserver(CompositorObserver* observer);
-  bool HasObserver(CompositorObserver* observer);
+  bool HasObserver(const CompositorObserver* observer) const;
 
   void AddAnimationObserver(CompositorAnimationObserver* observer);
   void RemoveAnimationObserver(CompositorAnimationObserver* observer);
-  bool HasAnimationObserver(CompositorAnimationObserver* observer);
+  bool HasAnimationObserver(const CompositorAnimationObserver* observer) const;
 
   // Creates a compositor lock. Returns NULL if it is not possible to lock at
   // this time (i.e. we're waiting to complete a previous unlock).
   scoped_refptr<CompositorLock> GetCompositorLock();
 
   // Internal functions, called back by command-buffer contexts on swap buffer
   // events.
 
   // Signals swap has been posted.
   void OnSwapBuffersPosted();
@@ skipping 106 matching lines @@
   LayerAnimatorCollection layer_animator_collection_;
 
   base::WeakPtrFactory<Compositor> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Compositor);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_COMPOSITOR_H_