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

webrtc/api/video/video_content_type.h

Index: webrtc/api/video/video_content_type.h
diff --git a/webrtc/api/video/video_content_type.h b/webrtc/api/video/video_content_type.h
index 5c468c079d35ea2d20c115234cf38d7e7fcd42bd..3b89978210f79320722b647ff72387f07b23a4f0 100644
--- a/webrtc/api/video/video_content_type.h
+++ b/webrtc/api/video/video_content_type.h
@@ -18,7 +18,20 @@ 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