Add read support of RtpStreamId/RepairedRtpStreamId header extensions.

webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc

 /*
  *  Copyright (c) 2016 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 226 matching lines @@
   }
   return false;
 }
 
 bool VideoContentTypeExtension::Write(uint8_t* data,
                                       VideoContentType content_type) {
   data[0] = static_cast<uint8_t>(content_type);
   return true;
 }
 
+// RtpStreamId.
+constexpr RTPExtensionType RtpStreamId::kId;
+constexpr uint8_t RtpStreamId::kValueSizeBytes;
+constexpr const char* RtpStreamId::kUri;
+
+bool RtpStreamId::Parse(rtc::ArrayView<const uint8_t> data, StreamId* rsid) {
+  if (data.empty() || data[0] == 0)  // Valid rsid can't be empty.
+    return false;
+  rsid->Set(data);
+  RTC_DCHECK(!rsid->empty());
+  return true;
+}
+
+bool RtpStreamId::Parse(rtc::ArrayView<const uint8_t> data, std::string* rsid) {
+  if (data.empty() || data[0] == 0)  // Valid rsid can't be empty.
+    return false;
+  const char* str = reinterpret_cast<const char*>(data.data());
+  // If there is a \0 character in the middle of the |data|, treat it as end of
+  // the string. Well-formed rsid shouldn't contain it.
+  rsid->assign(str, strnlen(str, data.size()));
+  RTC_DCHECK(!rsid->empty());
+  return true;
+}
+
+// RepairedRtpStreamId.
+constexpr RTPExtensionType RepairedRtpStreamId::kId;
+constexpr uint8_t RepairedRtpStreamId::kValueSizeBytes;
+constexpr const char* RepairedRtpStreamId::kUri;
+
+// RtpStreamId and RepairedRtpStreamId use the same format to store rsid.
+bool RepairedRtpStreamId::Parse(rtc::ArrayView<const uint8_t> data,
+                                StreamId* rsid) {
+  return RtpStreamId::Parse(data, rsid);
+}
+
+bool RepairedRtpStreamId::Parse(rtc::ArrayView<const uint8_t> data,
+                                std::string* rsid) {
+  return RtpStreamId::Parse(data, rsid);
+}
+
 }  // namespace webrtc