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

webrtc/sdk/android/src/jni/androidmediaencoder_jni.cc

Index: webrtc/sdk/android/src/jni/androidmediaencoder_jni.cc
diff --git a/webrtc/sdk/android/src/jni/androidmediaencoder_jni.cc b/webrtc/sdk/android/src/jni/androidmediaencoder_jni.cc
index 44acccf630db8983e3c7007e2b087c1e4576930d..1f4ba501fbdddc09f27a3637e37428897b460d75 100644
--- a/webrtc/sdk/android/src/jni/androidmediaencoder_jni.cc
+++ b/webrtc/sdk/android/src/jni/androidmediaencoder_jni.cc
@@ -1042,6 +1042,10 @@ bool MediaCodecVideoEncoder::DeliverPendingOutputs(JNIEnv* jni) {
       image->_timeStamp = output_timestamp_;
       image->capture_time_ms_ = output_render_time_ms_;
       image->rotation_ = output_rotation_;
+      if (codec_mode_ == webrtc::VideoCodecMode::kScreensharing)
+        image->content_type_ = webrtc::VideoContentType::kScreenshare;
+      else
+        image->content_type_ = webrtc::VideoContentType::kUnspecified;
       image->_frameType =
           (key_frame ? webrtc::kVideoFrameKey : webrtc::kVideoFrameDelta);
       image->_completeFrame = true;