Add read support of RtpStreamId/RepairedRtpStreamId header extensions.

webrtc/modules/rtp_rtcp/source/rtp_utility.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_utility.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_utility.cc b/webrtc/modules/rtp_rtcp/source/rtp_utility.cc
index def431f1709499993bac608a993aa0c49e33bc1b..6d7443c7e68b19e14a07180365c317c508489579 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_utility.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_utility.cc
@@ -446,6 +446,15 @@ void RtpHeaderParser::ParseOneByteExtensionHeader(
               max_playout_delay * PlayoutDelayLimits::kGranularityMs;
           break;
         }
+        case kRtpExtensionRtpStreamId: {
+          header->extension.stream_id.Set(rtc::MakeArrayView(ptr, len + 1));

[nisse-webrtc, 2017/04/11 10:42:53]

This (and kRtpExtensionRepairedRtpStreamId below) would also accept a length one
stream id containing only a nul-byte, right?

So for consistency, check if ptr[0] == 0, and ignore the extension in that case?

[danilchap, 2017/04/11 12:51:26]

Yes, but that would produce a stream_id that is .empty()
which is consistent with 'no extension was present' case.
Added test.

[nisse-webrtc, 2017/04/11 13:34:49]

Ok.

+          break;
+        }
+        case kRtpExtensionRepairedRtpStreamId: {
+          header->extension.repaired_stream_id.Set(
+              rtc::MakeArrayView(ptr, len + 1));
+          break;
+        }
         case kRtpExtensionNone:
         case kRtpExtensionNumberOfExtensions: {
           RTC_NOTREACHED() << "Invalid extension type: " << type;