Piggybacking simulcast id and ALR experiment id into video content type extension.

webrtc/api/video/video_content_type.h

 /*
  *  Copyright (c) 2017 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_VIDEO_VIDEO_CONTENT_TYPE_H_
 #define WEBRTC_API_VIDEO_VIDEO_CONTENT_TYPE_H_
 
 #include <stdint.h>
 
 namespace webrtc {
 
 enum class VideoContentType : uint8_t {
   UNSPECIFIED = 0,
   SCREENSHARE = 1,
-  TOTAL_CONTENT_TYPES  // Must be the last value in the enum.
+};
+
+struct VideoContentTypeHelpers {

[tommi, 2017/08/30 09:48:08]

nit: should this be a namespace instead of class+statics?

[ilnik, 2017/08/30 10:00:56]

Done.

+  static bool SetExperimentId(VideoContentType* content_type,
+                              uint8_t experiment_id);
+  static bool SetSimulcastId(VideoContentType* content_type,
+                             uint8_t simulcast_id);
+
+  static uint8_t GetExperimentId(const VideoContentType& content_type);
+  static uint8_t GetSimulcastId(const VideoContentType& content_type);
+
+  static bool IsScreenshare(const VideoContentType& content_type);
+
+  static bool IsValidContentType(uint8_t value);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_VIDEO_VIDEO_CONTENT_TYPE_H_