Add read support of RtpStreamId/RepairedRtpStreamId header extensions.

webrtc/common_types.h

Index: webrtc/common_types.h
diff --git a/webrtc/common_types.h b/webrtc/common_types.h
index 750420196d957bde26f094368c9a3cee11519196..06733be168d6a08e351d0b954a2e84b03a7e4991 100644
--- a/webrtc/common_types.h
+++ b/webrtc/common_types.h
@@ -20,6 +20,7 @@
 
 #include "webrtc/api/video/video_content_type.h"
 #include "webrtc/api/video/video_rotation.h"
+#include "webrtc/base/array_view.h"
 #include "webrtc/base/checks.h"
 #include "webrtc/base/optional.h"
 #include "webrtc/typedefs.h"
@@ -695,6 +696,42 @@ struct PlayoutDelay {
   int max_ms;
 };
 
+// Class to represent RtpStreamId which is a string.
+// Unlike std::string, it can be copied with memcpy and cleared with memset.
+// Empty value represent unset RtpStreamId.
+class StreamId {
+ public:
+  // Stream id is limited to 16 bytes because it is the maximum length
+  // that can be encoded with one-byte header extensions.
+  static constexpr size_t kMaxSize = 16;
+
+  StreamId() { value_[0] = 0; }
+  explicit StreamId(rtc::ArrayView<const char> value) {
+    Set(value.data(), value.size());
+  }
+  StreamId(const StreamId&) = default;
+  StreamId& operator=(const StreamId&) = default;
+
+  bool empty() const { return value_[0] == 0; }
+  const char* data() const { return value_; }
+  size_t size() const { return strnlen(value_, kMaxSize); }
+
+  void Set(rtc::ArrayView<const uint8_t> value) {
+    Set(reinterpret_cast<const char*>(value.data()), value.size());
+  }
+  void Set(const char* data, size_t size);
+
+  friend bool operator==(const StreamId& lhs, const StreamId& rhs) {
+    return strncmp(lhs.value_, rhs.value_, kMaxSize) == 0;
+  }
+  friend bool operator!=(const StreamId& lhs, const StreamId& rhs) {
+    return !(lhs == rhs);
+  }
+
+ private:
+  char value_[kMaxSize];
+};
+
 struct RTPHeaderExtension {
   RTPHeaderExtension();
 
@@ -723,6 +760,12 @@ struct RTPHeaderExtension {
   VideoContentType videoContentType;
 
   PlayoutDelay playout_delay = {-1, -1};
+
+  // For identification of a stream when ssrc is not signaled. See
+  // https://tools.ietf.org/html/draft-ietf-avtext-rid-09
+  // TODO(danilchap): Update url from draft to release version.
+  StreamId stream_id;
+  StreamId repaired_stream_id;
 };
 
 struct RTPHeader {