Wire up send-side bandwidth estimation.

BUG=webrtc:4173

Review URL: https://codereview.webrtc.org/1338203003

Cr-Commit-Position: refs/heads/master@{#10012}

webrtc/modules/rtp_rtcp/source/rtcp_sender.h

@@ -33,9 +33,6 @@ namespace webrtc {
 class ModuleRtpRtcpImpl;
 class RTCPReceiver;
 
-namespace rtcp {
-class TransportFeedback;
-}
 class NACKStringBuilder {
  public:
   NACKStringBuilder();