Adds injectable trials from peerconnection down to transport controller.

This will be immediately useful to guarantee consistent state across
components referencing the pacer, but will be a net benefit overall
imo.

Bug: webrtc:10809
Change-Id: I49630696f757a832ccf2e4c8597193bf087ce53b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/159885
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Commit-Queue: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29859}
diff --git a/api/BUILD.gn b/api/BUILD.gn
index 8bb4f24..6847a12 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -188,6 +188,7 @@
     "transport:datagram_transport_interface",
     "transport:enums",
     "transport:network_control",
+    "transport:webrtc_key_value_config",
     "transport/media:audio_interfaces",
     "transport/media:media_transport_interface",
     "transport/media:video_interfaces",