This avoids a data race in which the lifetime TimeInterval is accessed
by the owning Call objects concurrently with SendRtp calls on the
underlying Channel object.
Bug: webrtc:8794
Change-Id: If53d5680095c0177656b659162457287cb8e45dd
Reviewed-on: https://webrtc-review.googlesource.com/46525
Commit-Queue: Sam Zackrisson <saza@webrtc.org>
Reviewed-by: Fredrik Solenberg <solenberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21853}