ObserverList::HasObserver now takes a const pointer.

chromeos/dbus/fake_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_FAKE_CRAS_AUDIO_CLIENT_H_
 #define CHROMEOS_DBUS_FAKE_CRAS_AUDIO_CLIENT_H_
 
 #include "chromeos/chromeos_export.h"
 #include "chromeos/dbus/cras_audio_client.h"
 
 namespace chromeos {
 
 class CrasAudioHandlerTest;
 
 // The CrasAudioClient implementation used on Linux desktop.
 class CHROMEOS_EXPORT FakeCrasAudioClient : public CrasAudioClient {
  public:
   FakeCrasAudioClient();
   virtual ~FakeCrasAudioClient();
 
   // CrasAudioClient overrides:
   virtual void Init(dbus::Bus* bus) override;
   virtual void AddObserver(Observer* observer) override;
   virtual void RemoveObserver(Observer* observer) override;
-  virtual bool HasObserver(Observer* observer) override;
+  virtual bool HasObserver(const Observer* observer) const override;
   virtual void GetVolumeState(const GetVolumeStateCallback& callback) override;
   virtual void GetNodes(const GetNodesCallback& callback,
                         const ErrorCallback& error_callback) override;
   virtual void SetOutputNodeVolume(uint64 node_id, int32 volume) override;
   virtual void SetOutputUserMute(bool mute_on) override;
   virtual void SetInputNodeGain(uint64 node_id, int32 gain) override;
   virtual void SetInputMute(bool mute_on) override;
   virtual void SetActiveOutputNode(uint64 node_id) override;
   virtual void SetActiveInputNode(uint64 node_id) override;
   virtual void AddActiveInputNode(uint64 node_id) override;
@@ skipping 15 matching lines @@
   uint64 active_input_node_id_;
   uint64 active_output_node_id_;
   ObserverList<Observer> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeCrasAudioClient);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_FAKE_CRAS_AUDIO_CLIENT_H_