Remove unnecessary RTPHeaderParser, following https://codereview.webrtc.org/2659563002/

webrtc/call/call.cc

Index: webrtc/call/call.cc
diff --git a/webrtc/call/call.cc b/webrtc/call/call.cc
index 6fd0f6d74ad75f6cc9ceb4a6fd273988a83fc323..5e21fe531234ecf8c3137fbcb0fd3dd6b60fd74d 100644
--- a/webrtc/call/call.cc
+++ b/webrtc/call/call.cc
@@ -208,7 +208,7 @@ class Call : public webrtc::Call,
     // extensions per SSRC instead, which leads to some storage overhead.
     RtpHeaderExtensionMap extensions;
     // Set if the RTCP feedback message needed for send side BWE was negotiated.
-    bool transport_cc;
+    bool transport_cc = false;
   };
   std::map<uint32_t, ReceiveRtpConfig> receive_rtp_config_
       GUARDED_BY(receive_crit_);