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

webrtc/modules/bitrate_controller/include/bitrate_controller.h

Index: webrtc/modules/bitrate_controller/include/bitrate_controller.h
diff --git a/webrtc/modules/bitrate_controller/include/bitrate_controller.h b/webrtc/modules/bitrate_controller/include/bitrate_controller.h
index 032fec5fc7609a15023fe3faf6c841090c6f7c9c..36637a3dc0f9aec59bd01682cf91df7deb95694e 100644
--- a/webrtc/modules/bitrate_controller/include/bitrate_controller.h
+++ b/webrtc/modules/bitrate_controller/include/bitrate_controller.h
@@ -54,11 +54,11 @@ class BitrateController : public Module {
   // 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() {}