Resolve cyclic dependency in remote bitrate estimator

Access SendTransportFeedback function through new interface to break rbe -> pacing -> rbe cycle
Depend on rtp_rtcp_format source set to break rbe -> rtp_rtcp -> rbe cycle.

Bug: webrtc:6828
Change-Id: Iae1c463a71871c0055485e2eca9b2235d770afec
Reviewed-on: https://webrtc-review.googlesource.com/1620
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#19947}
diff --git a/modules/remote_bitrate_estimator/BUILD.gn b/modules/remote_bitrate_estimator/BUILD.gn
index d29969a..4784a83 100644
--- a/modules/remote_bitrate_estimator/BUILD.gn
+++ b/modules/remote_bitrate_estimator/BUILD.gn
@@ -9,11 +9,6 @@
 import("../../webrtc.gni")
 
 rtc_static_library("remote_bitrate_estimator") {
-  # TODO(mbonadei): Remove (bugs.webrtc.org/6828)
-  # Errors on cyclic dependency with:
-  # rtp_rtcp:rtp_rtcp if enabled.
-  check_includes = false
-
   sources = [
     "aimd_rate_control.cc",
     "aimd_rate_control.h",
@@ -51,7 +46,9 @@
 
   deps = [
     "../..:webrtc_common",
-    "../../rtc_base:rtc_base",
+    "../../api:optional",
+    "../../modules:module_api",
+    "../../modules/rtp_rtcp:rtp_rtcp_format",
     "../../rtc_base:rtc_base_approved",
     "../../system_wrappers",
   ]