Revert "Revert of Parse FlexFEC RTP headers in Call and add integration with BWE. (patchset #17 id:460001 of https://codereview.webrtc.org/2553863003/ )"

Problem fixed: RTP header extensions were not properly set in tests.

BUG=webrtc:5654

Review-Url: https://codereview.webrtc.org/2593963003
Cr-Commit-Position: refs/heads/master@{#15741}
diff --git a/webrtc/call/flexfec_receive_stream.h b/webrtc/call/flexfec_receive_stream.h
index 83b212b..20a57f2 100644
--- a/webrtc/call/flexfec_receive_stream.h
+++ b/webrtc/call/flexfec_receive_stream.h
@@ -59,7 +59,7 @@
     bool transport_cc = false;
 
     // RTP header extensions that have been negotiated for this track.
-    std::vector<RtpExtension> extensions;
+    std::vector<RtpExtension> rtp_header_extensions;
   };
 
   // Starts stream activity.