Send and receive color space information if available

Bug: webrtc:8651
Change-Id: I244647cb1ccbda66fce83ae925cf4273c5a6568b
Reviewed-on: https://webrtc-review.googlesource.com/c/112383
Commit-Queue: Johannes Kron <kron@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25884}
diff --git a/modules/rtp_rtcp/source/rtp_header_extensions.h b/modules/rtp_rtcp/source/rtp_header_extensions.h
index 42a6216..c1eaf8c 100644
--- a/modules/rtp_rtcp/source/rtp_header_extensions.h
+++ b/modules/rtp_rtcp/source/rtp_header_extensions.h
@@ -188,8 +188,8 @@
   static constexpr RTPExtensionType kId = kRtpExtensionColorSpace;
   static constexpr uint8_t kValueSizeBytes = 30;
   static constexpr uint8_t kValueSizeBytesWithoutHdrMetadata = 4;
-  // TODO(webrtc:8651): Change to a valid uri.
-  static constexpr const char kUri[] = "rtp-colorspace-uri-placeholder";
+  static constexpr const char kUri[] =
+      "http://www.webrtc.org/experiments/rtp-hdrext/color-space";
 
   static bool Parse(rtc::ArrayView<const uint8_t> data,
                     ColorSpace* color_space);