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This is a reland of f51b93d7

Original change's description:
> [Cast MRP] Stop mirroring immediately when a the tab is closed.
> 
> Bug: 1095764, b/159154368
> Change-Id: I36829467e3a6477499c76ae0b15e110acba00c89
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2346911
> Reviewed-by: Yuri Wiitala <miu@chromium.org>
> Commit-Queue: John Williams <jrw@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#803343}

Bug: 1095764
Bug: b/159154368
Change-Id: Ib3fbf021e10e48b3cb7289427ed130b01109a71d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2388153Reviewed-by: Yuri Wiitala <miu@chromium.org>
Commit-Queue: Yuri Wiitala <miu@chromium.org>
Auto-Submit: John Williams <jrw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804019}