Add content type information to encoded images and corresponding rtp extension header

webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc b/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc
index 167f29ee956ed5000c0da40007aa3a1867e954d4..b5bdd9af8c0a563ce0fe3840d45b236860a21570 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc
@@ -196,4 +196,29 @@ bool PlayoutDelayLimits::Write(uint8_t* data,
   return true;
 }
 
+// Video Content Type.
+//
+// E.g. default video or screenshare.
+//
+//    0                   1
+//    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |  ID   | len=0 | Content type  |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+constexpr RTPExtensionType VideoContentTypeExtension::kId;
+constexpr uint8_t VideoContentTypeExtension::kValueSizeBytes;
+constexpr const char* VideoContentTypeExtension::kUri;
+
+bool VideoContentTypeExtension::Parse(const uint8_t* data,
+                                      VideoContentType* content_type) {
+  *content_type = static_cast<VideoContentType>(data[0]);

[nisse-webrtc, 2017/04/06 09:23:22]

Maybe return false if the value on the wire is invalid?

[ilnik, 2017/04/06 10:04:49]

Done.

+  return true;
+}
+
+bool VideoContentTypeExtension::Write(uint8_t* data,
+                                      VideoContentType content_type) {
+  data[0] = static_cast<uint8_t>(content_type);
+  return true;
+}
+
 }  // namespace webrtc