Refactor voe::Channel to not use RtpReceiver.

Analogous to https://webrtc-review.googlesource.com/c/src/+/92398, for
RtpVideoStreamReceiver.

Bug: webrtc:7135
Change-Id: I0639f9982da2ed80edbcf900cf14f8ae982ef80c
Reviewed-on: https://webrtc-review.googlesource.com/93820
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Oskar Sundbom <ossu@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24309}
diff --git a/modules/rtp_rtcp/source/contributing_sources.h b/modules/rtp_rtcp/source/contributing_sources.h
index 64d7f52..1a4a572 100644
--- a/modules/rtp_rtcp/source/contributing_sources.h
+++ b/modules/rtp_rtcp/source/contributing_sources.h
@@ -24,6 +24,10 @@
 
 class ContributingSources {
  public:
+  // Set by the spec, see
+  // https://www.w3.org/TR/webrtc/#dom-rtcrtpreceiver-getcontributingsources
+  static constexpr int64_t kHistoryMs = 10 * rtc::kNumMillisecsPerSec;
+
   ContributingSources();
   ~ContributingSources();