Create //webrtc/api:libjingle_peerconnection_api + refactorings.

webrtc/api/mediatypes.h

+/*
+ *  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.
+ */
+
+#ifndef WEBRTC_API_MEDIATYPES_H_
+#define WEBRTC_API_MEDIATYPES_H_
+
+#include <string>
+
+namespace cricket {
+
+enum MediaType {
+  MEDIA_TYPE_AUDIO,
+  MEDIA_TYPE_VIDEO,
+  MEDIA_TYPE_DATA
+};
+
+std::string MediaTypeToString(MediaType type);
+
+}  // namespace cricket
+
+#endif  // WEBRTC_API_MEDIATYPES_H_