commit f92eaf26c9c54590bdaa2f4e2cc0aee8d031fde0
author David Bokan <bokan@chromium.org> Fri Mar 01 01:54:51 2019
committer Commit Bot <commit-bot@chromium.org> Fri Mar 01 01:54:51 2019
tree c7cad46650acd77503a0862ec7b82f031fd99d70
parent c9a56a176ba1dfa89bf1d8b22933bc253eab7195

[Reland] Synthetic input waits on compositor display

Reland #2 Note:
{
  Previously (re-)landed:
  https://crrev.com/b37e23cbd52ba447ab89c6d18f4ea0ecdc3fa5c0
  Reverted:
  https://crrev.com/a9aa35a2fb904074cddb4e2d889217a899177721

  More leaky tests. Though we now resolve gesture callbacks at the end
  of the test, the callback may come in after the test.

  This re-land fixes the leaky tests by finishing the
  test only once the gesture is completed. Previously landed CL uploaded
  as PS1, fixed in PS2.

  NOTE TO SHERIFF:
  If this is causing issues on the leak bots, please ping me or disble
  the test rather than reverting, if possible.
}

This CL makes synthetic input - the kind used in web tests and
telemetry (e.g. gpuBenchmarking.scrollBy) - wait until a CompositorFrame
has been submitted by the renderer and displayed by the display
compositor before resolving the completion callback. This means client
code that wants to wait until any observable side-effects of this input
is visible to further input need only wait on the gesture's completion
callback.

To give a motivating example: suppose we wish to write a test that
scrolls an out-of-process iframe into view and clicks on a button in the
frame. The code might look something like this:

gpuBenchmarking.smoothScroll(1000, () => {
  gpuBenchmarking.tap(0, 0);
});

This code contains a race today. The callback for smoothScroll is
invoked as soon as the ScrollEnd is received in the renderer. However,
until a new compositor frame is submitted from the renderer, the tap
may occur against stale hit testing geometry. This is a major source of
flakiness in our tests.

This CL fixes the problem by forcing the renderer to perform a full
redraw at the end of each gesture. The redraw produces a compositor
frame and we invoke the callback once the compositor frame is displayed.
We do this by reusing the RequestPresentation mechanism in RenderWidget.
RequestPresentation required two modifications to work in web tests
which use a single thread proxy with no scheduler:

 - LayerTreeHost::Composite needs to check the forced redraw flag to
   determine whether we need to raster, otherwise it won't produce a
   frame
 - RequestPresentation must request a main frame since there's no
   scheduler to perform the commit, which is what SetNeedsForcedRedraw
   requests.

The timing change exposed an issue in the
overlay-play-button-tap-to-hide.html test so this CL also cleans that
test up to listen to the animation changes in media controls properly.

Finally, it's possible we may get input in a RenderWidget that's not
currently displayed. e.g. A click event sent via ChromeDriver causes a
TouchStart followed by a TouchEnd. The TouchStart causes a window.open
which opens and focuses a new tab. The TouchEnd then happens on the
background tab. In this case, we should resolve the callback rather than
waiting on a CompositorFrame that'll never come. See ChromeDriver test
testNetworkConnectionTypeIsAppliedToAllTabs for an example of this.


TBR=dtapuska@chromium.org,nzolghadr@chromium.org,samans@chromium.org,peter@chromium.org

Bug: 902446
Change-Id: I0f818168b3f36070f72369a072e7f5eac64eb77c
Reviewed-on: https://chromium-review.googlesource.com/c/1496244
Commit-Queue: David Bokan <bokan@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636654}