Remove unneeded enum forward declaration

webrtc/modules/remote_bitrate_estimator/overuse_detector.h

 /*
  *  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 WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_OVERUSE_DETECTOR_H_
 #define WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_OVERUSE_DETECTOR_H_
 
 #include <list>
 
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/modules/include/module_common_types.h"
 #include "webrtc/modules/remote_bitrate_estimator/include/bwe_defines.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
-enum RateControlRegion;
 
 bool AdaptiveThresholdExperimentIsDisabled();
 
 class OveruseDetector {
  public:
   OveruseDetector();
   virtual ~OveruseDetector();
 
   // Update the detection state based on the estimated inter-arrival time delta
   // offset. |timestamp_delta| is the delta between the last timestamp which the
@@ skipping 22 matching lines @@
   double prev_offset_;
   double time_over_using_;
   int overuse_counter_;
   BandwidthUsage hypothesis_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(OveruseDetector);
 };
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_OVERUSE_DETECTOR_H_