Cleanup RtpHeaderExtensionMap removing use of two legacy functions

webrtc/modules/rtp_rtcp/source/rtp_header_parser.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_header_parser.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_header_parser.cc b/webrtc/modules/rtp_rtcp/source/rtp_header_parser.cc
index 2cec8a3e0f6c8c17ec4495ba74de0d0e54a112a2..ac0aeb176833bde3f75f7aa9520165e9104aaed4 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_header_parser.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_header_parser.cc
@@ -53,7 +53,7 @@ bool RtpHeaderParserImpl::Parse(const uint8_t* packet,
   RtpHeaderExtensionMap map;
   {
     rtc::CritScope cs(&critical_section_);
-    rtp_header_extension_map_.GetCopy(&map);
+    map = rtp_header_extension_map_;
   }
 
   const bool valid_rtpheader = rtp_parser.Parse(header, &map);
@@ -66,7 +66,7 @@ bool RtpHeaderParserImpl::Parse(const uint8_t* packet,
 bool RtpHeaderParserImpl::RegisterRtpHeaderExtension(RTPExtensionType type,
                                                      uint8_t id) {
   rtc::CritScope cs(&critical_section_);
-  return rtp_header_extension_map_.Register(type, id) == 0;
+  return rtp_header_extension_map_.RegisterByType(id, type);
 }
 
 bool RtpHeaderParserImpl::DeregisterRtpHeaderExtension(RTPExtensionType type) {