Create the SrtpTransportInterface.

webrtc/api/mediatypes.cc

Index: webrtc/api/mediatypes.cc
diff --git a/webrtc/api/mediatypes.cc b/webrtc/api/mediatypes.cc
index 97b0189b7a9349396219aa69a6df3adf5a124520..8b7ba3686b702587b61fdb90c444a868d5ddad7c 100644
--- a/webrtc/api/mediatypes.cc
+++ b/webrtc/api/mediatypes.cc
@@ -9,27 +9,37 @@
  */
 
 #include "webrtc/api/mediatypes.h"
+
+#include "webrtc/api/mediastreaminterface.h"
 #include "webrtc/base/checks.h"
 
+namespace {
+static const char* kMediaTypeData = "data";
+}  // namespace
+
 namespace cricket {
 
 std::string MediaTypeToString(MediaType type) {
-  std::string type_str;
   switch (type) {
     case MEDIA_TYPE_AUDIO:
-      type_str = "audio";
-      break;
+      return webrtc::MediaStreamTrackInterface::kAudioKind;
     case MEDIA_TYPE_VIDEO:
-      type_str = "video";
-      break;
+      return webrtc::MediaStreamTrackInterface::kVideoKind;
     case MEDIA_TYPE_DATA:
-      type_str = "data";
-      break;
-    default:
-      RTC_NOTREACHED();
-      break;
+      return kMediaTypeData;
+  }
+}
+
+MediaType MediaTypeFromString(const std::string& type_str) {
+  if (type_str == webrtc::MediaStreamTrackInterface::kAudioKind) {
+    return MEDIA_TYPE_AUDIO;
+  } else if (type_str == webrtc::MediaStreamTrackInterface::kVideoKind) {
+    return MEDIA_TYPE_VIDEO;
+  } else if (type_str == kMediaTypeData) {
+    return MEDIA_TYPE_DATA;
+  } else {
+    FATAL();
   }
-  return type_str;
 }
 
 }  // namespace cricket