ObserverList::HasObserver now takes a const pointer.

chromeos/dbus/cras_audio_client.h

 // Copyright (c) 2013 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 CHROMEOS_DBUS_CRAS_AUDIO_CLIENT_H_
 #define CHROMEOS_DBUS_CRAS_AUDIO_CLIENT_H_
 
 #include "base/callback.h"
 #include "base/observer_list.h"
 #include "chromeos/chromeos_export.h"
@@ skipping 31 matching lines @@
    protected:
     virtual ~Observer();
   };
 
   virtual ~CrasAudioClient();
 
   // Adds and removes the observer.
   virtual void AddObserver(Observer* observer) = 0;
   virtual void RemoveObserver(Observer* observer) = 0;
   // Returns true if this object has the given observer.
-  virtual bool HasObserver(Observer* observer) = 0;
+  virtual bool HasObserver(const Observer* observer) const = 0;
 
   // GetVolumeStateCallback is used for GetVolumeState method. It receives
   // 2 arguments, |volume_state| which containing both input and  output volume
   // state data, and |success| which indicates whether or not the request
   // succeeded.
   typedef base::Callback<void(const VolumeState&, bool)> GetVolumeStateCallback;
 
   // GetNodesCallback is used for GetNodes method. It receives 2 arguments,
   // |audio_nodes| which containing a list of audio nodes data and
   // |success| which indicates whether or not the request succeeded.
@@ skipping 66 matching lines @@
   // Create() should be used instead.
   CrasAudioClient();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CrasAudioClient);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_CRAS_AUDIO_CLIENT_H_