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As requested in https://chromium-review.googlesource.com/c/chromium/src/+/1860015
I've added a test to ensure that when adding a quiet permission request, it
will be killed by a loud one.

Bug: 1014026
Change-Id: Ic966af5752356917d8a47929be67e8e189aeb642
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1873925
Commit-Queue: Andy Paicu <andypaicu@chromium.org>
Reviewed-by: Balazs Engedy <engedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708552}