Cleanup RtpHeaderExtensionMap removing use of two legacy functions

webrtc/modules/rtp_rtcp/source/rtp_utility.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_utility.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_utility.cc b/webrtc/modules/rtp_rtcp/source/rtp_utility.cc
index 7dd59736fd044d855d0ae11ed146bd327c948e7f..cc0d650a5cd01c61370852e127d5f5ea25b156a9 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_utility.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_utility.cc
@@ -331,8 +331,8 @@ void RtpHeaderParser::ParseOneByteExtensionHeader(
       return;
     }
 
-    RTPExtensionType type;
-    if (ptrExtensionMap->GetType(id, &type) != 0) {
+    RTPExtensionType type = ptrExtensionMap->GetType(id);
+    if (type == RtpHeaderExtensionMap::kInvalidType) {
       // If we encounter an unknown extension, just skip over it.
       LOG(LS_WARNING) << "Failed to find extension id: " << id;
     } else {
@@ -439,8 +439,9 @@ void RtpHeaderParser::ParseOneByteExtensionHeader(
               max_playout_delay * kPlayoutDelayGranularityMs;
           break;
         }
-        default: {
-          LOG(LS_WARNING) << "Extension type not implemented: " << type;
+        case kRtpExtensionNone:
+        case kRtpExtensionNumberOfExtensions: {
+          RTC_NOTREACHED() << "Invalid extension type: " << type;
           return;
         }
       }