Looks like each of these three tests have non-trivial problems:

[element-ready-check-allowed-cross-origin-manual.sub.html]
We can't pass in an iframe's document (elem.contentDocument) as a container for simulated click because the contentDocument in the cross-origin subframe is inaccessible from top frame.
https://cs.chromium.org/chromium/src/third_party/WebKit/LayoutTests/external/wpt/fullscreen/api/element-ready-check-allowed-cross-origin-manual.sub.html?rcl=15e3f4d323ca3f04e7f3c63c453906c0166a33ea&l=29


[element-ready-check-containing-iframe-manual.html]
We could use the fix we suggested for the above test, but the problem is in Chrome's automation script: auto-click.js sends mouse clicks to all buttons it finds in the page, but this test adds the second button /after/ first click is handled.  As a result, auto-click.js never finds a second button.  This passes w/o UAv2 because the first click activation is used in both cases (and will start failing if we consume activation, Issue 852645).

I guess this is a problem with all other fullscreen tests that have addButton1-handleClick1-addButton2-handleClick2 like sequencing, but I didn't investigate.


[external/wpt/fullscreen/api/element-request-fullscreen-two-iframes-manual.html]
This test is incompatible with UAv2: a single user activation can't be utilized from two sibling frames.

Found a fix for second+third tests above.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9be178a81a5496feb02a08aaac24e03fdf68fd32

commit 9be178a81a5496feb02a08aaac24e03fdf68fd32
Author: Mustaq Ahmed <mustaq@google.com>
Date: Fri Nov 23 18:42:45 2018

Fix two fullscreen wpt tests for UAv2.

Also marks one currently untestable test.

Bug:  906791 
Change-Id: I17fd03f16e93244be80f9572db8c43e8e0b95678
Reviewed-on: https://chromium-review.googlesource.com/c/1347092
Commit-Queue: Mustaq Ahmed <mustaq@chromium.org>
Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610651}
[modify] https://crrev.com/9be178a81a5496feb02a08aaac24e03fdf68fd32/third_party/WebKit/LayoutTests/TestExpectations
[modify] https://crrev.com/9be178a81a5496feb02a08aaac24e03fdf68fd32/third_party/WebKit/LayoutTests/external/wpt/fullscreen/api/element-ready-check-allowed-cross-origin-manual.sub.html
[add] https://crrev.com/9be178a81a5496feb02a08aaac24e03fdf68fd32/third_party/WebKit/LayoutTests/external/wpt/fullscreen/api/element-ready-check-containing-iframe-manual.tentative.html
[modify] https://crrev.com/9be178a81a5496feb02a08aaac24e03fdf68fd32/third_party/WebKit/LayoutTests/external/wpt/fullscreen/api/element-request-fullscreen-two-iframes-manual.html