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

webrtc/modules/remote_bitrate_estimator/include/bwe_defines.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_INCLUDE_BWE_DEFINES_H_
 #define WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_INCLUDE_BWE_DEFINES_H_
 
 #include "webrtc/base/optional.h"
 #include "webrtc/typedefs.h"
 
 #define BWE_MAX(a, b) ((a) > (b) ? (a) : (b))
 #define BWE_MIN(a, b) ((a) < (b) ? (a) : (b))
 
 namespace webrtc {
 
+namespace congestion_controller {
+int GetMinBitrateBps();
+}  // namespace congestion_controller
+
 static const int64_t kBitrateWindowMs = 1000;
 
 extern const char* kBweTypeHistogram;
 
 enum BweNames {
   kReceiverNoExtension = 0,
   kReceiverTOffset = 1,
   kReceiverAbsSendTime = 2,
   kSendSideTransportSeqNum = 3,
   kBweNamesMax = 4
@@ skipping 17 matching lines @@
         incoming_bitrate(incoming_bitrate),
         noise_var(noise_var) {}
 
   BandwidthUsage bw_state;
   rtc::Optional<uint32_t> incoming_bitrate;
   double noise_var;
 };
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_INCLUDE_BWE_DEFINES_H_