Create //webrtc/api:libjingle_peerconnection_api + refactorings.

webrtc/api/mediatypes.cc

+/*
+ *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/api/mediatypes.h"
+#include "webrtc/base/checks.h"
+
+namespace cricket {
+
+std::string MediaTypeToString(MediaType type) {
+  std::string type_str;
+  switch (type) {
+    case MEDIA_TYPE_AUDIO:
+      type_str = "audio";
+      break;
+    case MEDIA_TYPE_VIDEO:
+      type_str = "video";
+      break;
+    case MEDIA_TYPE_DATA:
+      type_str = "data";
+      break;
+    default:
+      RTC_NOTREACHED();
+      break;
+  }
+  return type_str;
+}
+
+}  // namespace cricket