Add RSID-based demuxing to RtpDemuxer

webrtc/common_types.h

Index: webrtc/common_types.h
diff --git a/webrtc/common_types.h b/webrtc/common_types.h
index 424afd91397414a18c6f8d96e45da4d4a73f36db..e5bfcd2901fe7645d16595ceabf1089b4cb8be4b 100644
--- a/webrtc/common_types.h
+++ b/webrtc/common_types.h
@@ -707,6 +707,8 @@ class StreamId {
   // that can be encoded with one-byte header extensions.
   static constexpr size_t kMaxSize = 16;
 
+  static bool IsLegalName(rtc::ArrayView<const char> name);
+
   StreamId() { value_[0] = 0; }
   explicit StreamId(rtc::ArrayView<const char> value) {
     Set(value.data(), value.size());