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

webrtc/modules/include/module_common_types.h

Index: webrtc/modules/include/module_common_types.h
diff --git a/webrtc/modules/include/module_common_types.h b/webrtc/modules/include/module_common_types.h
index a16c9392a2ec62a3d46ae42a47223c092c141745..ffa07980a08c1e1090afb5fb29cf814c7df900fb 100644
--- a/webrtc/modules/include/module_common_types.h
+++ b/webrtc/modules/include/module_common_types.h
@@ -58,6 +58,8 @@
 
   PlayoutDelay playout_delay;
 
+  VideoContentType content_type;
+
   union {
     bool is_first_packet_in_frame;
     RTC_DEPRECATED bool isFirstPacket;  // first packet in frame
@@ -87,7 +89,7 @@
         fragmentationOffset(NULL),
         fragmentationLength(NULL),
         fragmentationTimeDiff(NULL),
-        fragmentationPlType(NULL) {};
+        fragmentationPlType(NULL) {}
 
   ~RTPFragmentationHeader() {
     delete[] fragmentationOffset;