Clean out unused methods from VoiceEngine and VoEBase.

voice_engine/mock/mock_voe_observer.h

Index: voice_engine/mock/mock_voe_observer.h
diff --git a/voice_engine/mock/mock_voe_observer.h b/voice_engine/mock/mock_voe_observer.h
deleted file mode 100644
index 99c8c55fe136e7d9117044af67e4271ed56bf0bd..0000000000000000000000000000000000000000
--- a/voice_engine/mock/mock_voe_observer.h
+++ /dev/null
@@ -1,29 +0,0 @@
-/*
- *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#ifndef VOICE_ENGINE_MOCK_VOE_OBSERVER_H_
-#define VOICE_ENGINE_MOCK_VOE_OBSERVER_H_
-
-#include "test/gmock.h"
-#include "voice_engine/include/voe_base.h"
-
-namespace webrtc {
-
-class MockVoEObserver: public VoiceEngineObserver {
- public:
-  MockVoEObserver() {}
-  virtual ~MockVoEObserver() {}
-
-  MOCK_METHOD2(CallbackOnError, void(int channel, int error_code));
-};
-
-}
-
-#endif  // VOICE_ENGINE_MOCK_VOE_OBSERVER_H_