Set min BWE bitrate form 10kbps to 5kbps and centralize minimum bitrate.

webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.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.
  */
 
@@ skipping 26 matching lines @@
   virtual void OnProbeBitrate(uint32_t bitrate) {}
 
   virtual ~RemoteBitrateObserver() {}
 };
 
 // TODO(holmer): Remove when all implementations have been updated.
 struct ReceiveBandwidthEstimatorStats {};
 
 class RemoteBitrateEstimator : public CallStatsObserver, public Module {
  public:
-  static const int kDefaultMinBitrateBps = 30000;
   virtual ~RemoteBitrateEstimator() {}
 
   virtual void IncomingPacketFeedbackVector(
       const std::vector<PacketInfo>& packet_feedback_vector) {
     assert(false);
   }
 
   // Called for each incoming packet. Updates the incoming payload bitrate
   // estimate and the over-use detector. If an over-use is detected the
   // remote bitrate estimate will be updated. Note that |payload_size| is the
@@ skipping 20 matching lines @@
   virtual void SetMinBitrate(int min_bitrate_bps) = 0;
 
  protected:
   static const int64_t kProcessIntervalMs = 500;
   static const int64_t kStreamTimeOutMs = 2000;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_INCLUDE_REMOTE_BITRATE_ESTIMATOR_H_