[PEPC] Close PEPC prompt on tab switch

As per the DD the PEPC prompt should be closed when tab switching.

This CL introduces a new TabSwitchingBehavior that closes the request
as "Ignored" but also calls the "Cancelled" callback. This is needed
to allow PEPC requests to notify the renderer of the prompt being closed
in order to raise the "dismiss" event.

Additionally during this CL a flaw was identified in
PermissionElementBrowserTest which allowed all tests to falsely
pass. |waitForResolveEvent| would immediately return true which
made it appear that all conditions are met. This CL fixes that
by using console logs to determine which events have been raised so far,
and checking that they are the expected ones.

Fixed: 339792166
Change-Id: I3671f0b425c54ed889fa24484ed0e09d1ecb6884
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5526465


Commit-Queue: Andy Paicu <andypaicu@chromium.org>
Reviewed-by: Thomas Nguyen <tungnh@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1300313}