Delete deprecated constructor of SendSideCongestionController.

Move packet_router #include to where it's needed, and delete unused
MockPacketRouter.

Bug: webrtc:6847
Change-Id: I03c86c6fb8b413f5a535a237fa1724cc10960ffa
Reviewed-on: https://webrtc-review.googlesource.com/17320
Commit-Queue: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20564}
diff --git a/call/BUILD.gn b/call/BUILD.gn
index cb5d341..6a4f065 100644
--- a/call/BUILD.gn
+++ b/call/BUILD.gn
@@ -84,6 +84,7 @@
     ":rtp_interfaces",
     "..:webrtc_common",
     "../modules/congestion_controller",
+    "../modules/pacing",
     "../rtc_base:rtc_base_approved",
   ]
 }