commit 3afc7b5bf678afb3ae26517ea6f31f73cb385147
author Stephen Chenney <schenney@chromium.org> Fri Mar 19 19:08:55 2021
committer Blink WPT Bot <blink-w3c-test-autoroller@chromium.org> Fri Mar 19 20:00:16 2021
tree 5534d4ddbeda2a4814de53ee4db46e94d64c8c80
parent c36fafed84c9dd16cfa38f66a84ccca5cf32b3e4

Enable Paint Holding Cross Origin for tests

The Paint Holding Cross Origin feature extends Paint Holding to most
navigations. Paint Holding defers the first commit of rendering
data from the main thread to the compositor until after First
Contentful Paint, or a 500ms timeout, has occurred.

From a test perspective, the most important change is related to input.
We drop all input when not updating the document lifecycle and while
deferring the commits. Many tests expect to navigate and then immediately
process input, and these tests timeout or otherwise fail with
Paint Holding.

Three strategies have been employed to address this:
- For many tests it is sufficient to add text to the html content
  so that First Contentful Paint is reached upon load and commits
  begin. This works well for most cases but unfortunately the
  linux_chromeos_rel bot is still flaky, probably due to slower loading.
- Some tests just need to wait for hit test data, using
  WaitForHitTestData
- In other cases we allow early input using the blink flag.

Test coverage for Paint Holding is provided by essentially all
tests that use input or require a rendered result, so there is
little concern about using the early input flag in a few test suites.

This change may cause increased flakiness, particularly on the
linux-chromeos-rel bot and Android. Please assign flakiness bugs
to schenney@ and ping if necessary.

Bug: 1120158
Change-Id: Ief45735c5bdb4d48d6554dcfc12e3b621355e080
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2368282
Reviewed-by: Clemens Arbesser <arbesser@google.com>
Reviewed-by: Stephen McGruer <smcgruer@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Reviewed-by: Owen Min <zmin@chromium.org>
Reviewed-by: Eric Willigers <ericwilligers@chromium.org>
Reviewed-by: Tommy Martino <tmartino@chromium.org>
Commit-Queue: Stephen Chenney <schenney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#864725}