Add SEI to the list of packets counted as keyframe.

webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc b/webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc
index c422577c812cd80278daf73d3d0d64257fc50256..86b6f6ecd6b58efd16d7847ac32110b8a8407e27 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_format_h264.cc
@@ -101,6 +101,7 @@ bool ParseSingleNalu(RtpDepacketizer::ParsedPayload* parsed_payload,
   switch (nal_type) {
     case kSps:
     case kPps:
+    case kSei:
     case kIdr:
       parsed_payload->frame_type = kVideoFrameKey;
       break;