Add read support of RtpStreamId/RepairedRtpStreamId header extensions.

webrtc/modules/rtp_rtcp/source/rtp_utility.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 428 matching lines @@
           //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
           int min_playout_delay = (ptr[0] << 4) | ((ptr[1] >> 4) & 0xf);
           int max_playout_delay = ((ptr[1] & 0xf) << 8) | ptr[2];
           header->extension.playout_delay.min_ms =
               min_playout_delay * PlayoutDelayLimits::kGranularityMs;
           header->extension.playout_delay.max_ms =
               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;
           return;
         }
       }
     }
     ptr += (len + 1);
   }
 }
 
 }  // namespace RtpUtility
 }  // namespace webrtc