Add separate send-side UMA stats for screenshare and video.

webrtc/video/video_send_stream.cc

Index: webrtc/video/video_send_stream.cc
diff --git a/webrtc/video/video_send_stream.cc b/webrtc/video/video_send_stream.cc
index bc59900eff5cbd2c4d362df0742ab49d2482317f..3bc026cd2c9c018e9c884d4859d6e9b5faaa6461 100644
--- a/webrtc/video/video_send_stream.cc
+++ b/webrtc/video/video_send_stream.cc
@@ -117,7 +117,9 @@ VideoSendStream::VideoSendStream(
     const VideoSendStream::Config& config,
     const VideoEncoderConfig& encoder_config,
     const std::map<uint32_t, RtpState>& suspended_ssrcs)
-    : stats_proxy_(Clock::GetRealTimeClock(), config),
+    : stats_proxy_(Clock::GetRealTimeClock(),
+                   config,
+                   encoder_config.content_type),
       transport_adapter_(config.send_transport),
       encoded_frame_proxy_(config.post_encode_callback),
       config_(config),
@@ -435,6 +437,8 @@ bool VideoSendStream::ReconfigureVideoEncoder(
     stats_proxy_.OnInactiveSsrc(config_.rtp.ssrcs[i]);
   }
 
+  stats_proxy_.SetContentType(config.content_type);
+
   RTC_DCHECK_GE(config.min_transmit_bitrate_bps, 0);
   vie_encoder_->SetMinTransmitBitrate(config.min_transmit_bitrate_bps / 1000);