Update RateStatistics to handle too-little-data case.

webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_single_stream.h

 /*
  *  Copyright (c) 2015 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 38 matching lines @@
   // Triggers a new estimate calculation.
   void UpdateEstimate(int64_t time_now)
       EXCLUSIVE_LOCKS_REQUIRED(crit_sect_.get());
 
   void GetSsrcs(std::vector<uint32_t>* ssrcs) const
       SHARED_LOCKS_REQUIRED(crit_sect_.get());
 
   Clock* clock_;
   SsrcOveruseEstimatorMap overuse_detectors_ GUARDED_BY(crit_sect_.get());
   RateStatistics incoming_bitrate_ GUARDED_BY(crit_sect_.get());
+  uint32_t last_valid_incoming_bitrate_ GUARDED_BY(crit_sect_.get());
   std::unique_ptr<AimdRateControl> remote_rate_ GUARDED_BY(crit_sect_.get());
   RemoteBitrateObserver* observer_ GUARDED_BY(crit_sect_.get());
   std::unique_ptr<CriticalSectionWrapper> crit_sect_;
   int64_t last_process_time_;
   int64_t process_interval_ms_ GUARDED_BY(crit_sect_.get());
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(RemoteBitrateEstimatorSingleStream);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_REMOTE_BITRATE_ESTIMATOR_SINGLE_STREAM_H_