Add write support for the RtpStreamId and RepairedRtpStreamId header extensions.

webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc b/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc
index 13f488b09a8a2416968e072854540746df600146..d86f37e62ad0d64df34a6caaf297825424ba180b 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc
@@ -257,6 +257,11 @@ bool RtpStreamId::Parse(rtc::ArrayView<const uint8_t> data, StreamId* rsid) {
   return true;
 }
 
+bool RtpStreamId::Write(uint8_t* data, const StreamId& rsid) {
+  memcpy(data, rsid.data(), rsid.size());
+  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;
@@ -268,6 +273,11 @@ bool RtpStreamId::Parse(rtc::ArrayView<const uint8_t> data, std::string* rsid) {
   return true;
 }
 
+bool RtpStreamId::Write(uint8_t* data, const std::string& rsid) {
+  memcpy(data, rsid.data(), rsid.size());
+  return true;
+}
+
 // RepairedRtpStreamId.
 constexpr RTPExtensionType RepairedRtpStreamId::kId;
 constexpr uint8_t RepairedRtpStreamId::kValueSizeBytes;
@@ -279,9 +289,17 @@ bool RepairedRtpStreamId::Parse(rtc::ArrayView<const uint8_t> data,
   return RtpStreamId::Parse(data, rsid);
 }
 
+bool RepairedRtpStreamId::Write(uint8_t* data, const StreamId& rsid) {
+  return RtpStreamId::Write(data, rsid);
+}
+
 bool RepairedRtpStreamId::Parse(rtc::ArrayView<const uint8_t> data,
                                 std::string* rsid) {
   return RtpStreamId::Parse(data, rsid);
 }
 
+bool RepairedRtpStreamId::Write(uint8_t* data, const std::string& rsid) {
+  return RtpStreamId::Write(data, rsid);
+}
+
 }  // namespace webrtc