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..c3960b966509713fcd7faa5b61ffab78bffad2eb 100644
--- a/webrtc/api/video/video_content_type.h
+++ b/webrtc/api/video/video_content_type.h
@@ -18,9 +18,19 @@ namespace webrtc {
 enum class VideoContentType : uint8_t {
   UNSPECIFIED = 0,
   SCREENSHARE = 1,
-  TOTAL_CONTENT_TYPES  // Must be the last value in the enum.
 };
 
+namespace VideoContentTypeHelpers {

[kwiberg-webrtc, 2017/08/29 20:58:53]

"Namespace names are all lower-case." See
https://google.github.io/styleguide/cppguide.html#Namespace_Names

However, it may make more sense to make a struct with static methods instead of
a namespace; you can't open it up later and add more stuff, and there are fewer
dangerous name lookup rules.

[ilnik, 2017/08/30 07:36:06]

Great idea. Done.

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