Simplify registration of RTP-header extensions.

webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc b/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
index 7f33bc2ee57c1dc2b44aeade3feaaaf87f8072a2..46e5bcf00e4adf3bc2e2b7209166a60ba9d2520b 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
@@ -17,6 +17,7 @@
 #include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/common_types.h"
+#include "webrtc/config.h"
 #include "webrtc/system_wrappers/include/trace.h"
 
 #ifdef _WIN32
@@ -26,6 +27,21 @@
 
 namespace webrtc {
 
+RTPExtensionType StringToRtpExtensionType(const std::string& extension) {
+  if (extension == RtpExtension::kTOffset)
+    return kRtpExtensionTransmissionTimeOffset;
+  if (extension == RtpExtension::kAudioLevel)
+    return kRtpExtensionAudioLevel;
+  if (extension == RtpExtension::kAbsSendTime)
+    return kRtpExtensionAbsoluteSendTime;
+  if (extension == RtpExtension::kVideoRotation)
+    return kRtpExtensionVideoRotation;
+  if (extension == RtpExtension::kTransportSequenceNumber)
+    return kRtpExtensionTransportSequenceNumber;
+  RTC_NOTREACHED() << "Looking up unsupported RTP extension.";
+  return kRtpExtensionNone;
+}
+
 RtpRtcp::Configuration::Configuration()
     : audio(false),
       receiver_only(false),