Reland "Fix the failing xr browser transition tests."

This is a reland of 7c12dfff2924cd06dd30678318ad9dcc6fd04d6b

The test was failing because WebVR tests do not expect a consent dialog
but the code was waiting on one. This got fixed by overriding the method
in WebVrTestFramework.

Original change's description:
> Fix the failing xr browser transition tests.
>
> testNfcFiresVrdisplayactivate() - fixed by adding the automatic consent dialog handling code.
> testPresentationPromiseRejectedIfDonCanceled_WebXr() - fixed by specifying
> --shared-prefs-file=//chrome/android/shared_preference_files/test/vr_ddview_don_setupcomplete.json
>
> For the second test, the shared-prefs must be updated on the swarm bots to avoid getting
> into a regression.
>
> Bug: 969024
> Change-Id: Iaf88f9c202746eca32f7d8386c852eec43824757
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1645633
> Commit-Queue: Suman Kancherla <sumankancherla@chromium.org>
> Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#666586}

Bug: 969024
Change-Id: Ib3a2859c535501b84cf30279a15eb57822f7a55e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1648276
Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Commit-Queue: Suman Kancherla <sumankancherla@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666921}