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

webrtc/modules/bitrate_controller/include/bitrate_controller.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.
  *
  *  Usage: this class will register multiple RtcpBitrateObserver's one at each
@@ skipping 36 matching lines @@
   // This class collects feedback from all streams sent to a peer (via
   // RTCPBandwidthObservers). It does one  aggregated send side bandwidth
   // estimation and divide the available bitrate between all its registered
   // BitrateObservers.
  public:
   static const int kDefaultStartBitratebps = 300000;
 
   // Deprecated:
   // TODO(perkj): BitrateObserver has been deprecated and is not used in WebRTC.
   // Remove this method once other other projects does not use it.
-  static BitrateController* CreateBitrateController(Clock* clock,
+  static BitrateController* CreateBitrateController(const Clock* clock,
                                                     BitrateObserver* observer,
                                                     RtcEventLog* event_log);
 
-  static BitrateController* CreateBitrateController(Clock* clock,
+  static BitrateController* CreateBitrateController(const Clock* clock,
                                                     RtcEventLog* event_log);
 
   virtual ~BitrateController() {}
 
   virtual RtcpBandwidthObserver* CreateRtcpBandwidthObserver() = 0;
 
   // Deprecated
   virtual void SetStartBitrate(int start_bitrate_bps) = 0;
   // Deprecated
   virtual void SetMinMaxBitrate(int min_bitrate_bps, int max_bitrate_bps) = 0;
@@ skipping 12 matching lines @@
   virtual bool AvailableBandwidth(uint32_t* bandwidth) const = 0;
 
   virtual void SetReservedBitrate(uint32_t reserved_bitrate_bps) = 0;
 
   virtual bool GetNetworkParameters(uint32_t* bitrate,
                                     uint8_t* fraction_loss,
                                     int64_t* rtt) = 0;
 };
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_BITRATE_CONTROLLER_INCLUDE_BITRATE_CONTROLLER_H_