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

webrtc/modules/congestion_controller/transport_feedback_adapter.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.
  */
 
 #ifndef WEBRTC_MODULES_CONGESTION_CONTROLLER_TRANSPORT_FEEDBACK_ADAPTER_H_
 #define WEBRTC_MODULES_CONGESTION_CONTROLLER_TRANSPORT_FEEDBACK_ADAPTER_H_
 
 #include <vector>
 
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/thread_annotations.h"
 #include "webrtc/base/thread_checker.h"
 #include "webrtc/modules/remote_bitrate_estimator/include/send_time_history.h"
 #include "webrtc/system_wrappers/include/clock.h"
 
 namespace webrtc {
 
 namespace rtcp {
 class TransportFeedback;
 }  // namespace rtcp
 
 class TransportFeedbackAdapter {
  public:
-  explicit TransportFeedbackAdapter(Clock* clock);
+  explicit TransportFeedbackAdapter(const Clock* clock);
   virtual ~TransportFeedbackAdapter();
 
   void AddPacket(uint16_t sequence_number,
                  size_t length,
                  const PacedPacketInfo& pacing_info);
   void OnSentPacket(uint16_t sequence_number, int64_t send_time_ms);
 
   // TODO(holmer): This method should return DelayBasedBwe::Result so that we
   // can get rid of the dependency on BitrateController. Requires changes
   // to the CongestionController interface.
@@ skipping 14 matching lines @@
   SendTimeHistory send_time_history_ GUARDED_BY(&lock_);
   const Clock* const clock_;
   int64_t current_offset_ms_;
   int64_t last_timestamp_us_;
   std::vector<PacketFeedback> last_packet_feedback_vector_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_CONGESTION_CONTROLLER_TRANSPORT_FEEDBACK_ADAPTER_H_