Mark |Clock*| as |const Clock*| (for some CongestionController and BWE related modules)

webrtc/base/rate_limiter.cc

 /*
  *  Copyright (c) 2016 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.
  */
 
 #include "webrtc/base/rate_limiter.h"
 #include "webrtc/system_wrappers/include/clock.h"
 
 namespace webrtc {
 
-RateLimiter::RateLimiter(Clock* clock, int64_t max_window_ms)
+RateLimiter::RateLimiter(const Clock* clock, int64_t max_window_ms)
     : clock_(clock),
       current_rate_(max_window_ms, RateStatistics::kBpsScale),
       window_size_ms_(max_window_ms),
       max_rate_bps_(std::numeric_limits<uint32_t>::max()) {}
 
 RateLimiter::~RateLimiter() {}
 
 // Usage note: This class is intended be usable in a scenario where different
 // threads may call each of the the different method. For instance, a network
 // thread trying to send data calling TryUseRate(), the bandwidth estimator
@@ skipping 29 matching lines @@
 // Set the window size over which to measure the current bitrate.
 // For retransmissions, this is typically the RTT.
 bool RateLimiter::SetWindowSize(int64_t window_size_ms) {
   rtc::CritScope cs(&lock_);
   window_size_ms_ = window_size_ms;
   return current_rate_.SetWindowSize(window_size_ms,
                                      clock_->TimeInMilliseconds());
 }
 
 }  // namespace webrtc