[H264][Simulcast] Implement the simulcast logic for h264 encoder

webrtc/video/send_statistics_proxy.cc

Index: webrtc/video/send_statistics_proxy.cc
diff --git a/webrtc/video/send_statistics_proxy.cc b/webrtc/video/send_statistics_proxy.cc
index b8fdef2ca639c96d99dd59d2f084a17bed6371c4..723e50f714b0da69c65c66b0ac7f1f07ae5d6d18 100644
--- a/webrtc/video/send_statistics_proxy.cc
+++ b/webrtc/video/send_statistics_proxy.cc
@@ -431,6 +431,8 @@ void SendStatisticsProxy::OnSendEncodedImage(
   if (codec_info) {
     if (codec_info->codecType == kVideoCodecVP8) {
       simulcast_idx = codec_info->codecSpecific.VP8.simulcastIdx;
+    } else if (codec_info->codecType == kVideoCodecH264) {
+      simulcast_idx = codec_info->codecSpecific.H264.simulcastIdx;
     } else if (codec_info->codecType == kVideoCodecGeneric) {
       simulcast_idx = codec_info->codecSpecific.generic.simulcast_idx;
     }