commit e6ca4549d7316c39bc038027769326247a85a418
author David Bokan <bokan@chromium.org> Fri May 17 18:32:18 2019
committer Commit Bot <commit-bot@chromium.org> Fri May 17 18:32:18 2019
tree 802ee000a92a6c7c7333d0649f315123ae715329
parent 1dc2e479cc528e8fea55ac6773d172198e89cdeb

[BGPT] Update cc::Layer offset from visual viewport

In the linked bug, we try scrolling the page using the keyboard. While
all the scroll offsets in Blink are correctly updated, we don't see the
scrolling occur on the screen.

The reason for this is that we don't realize anything has changed and
the commit is aborted due to no changes. It turns out we don't update
the offset on the VisualViewport's cc::Layer. The reason this doesn't
manifest in other contexts is that we usually perform viewport scrolling
using touch or wheel events which are handled on the compositor thread.

The fix here is to do what we do for PaintLayerScrollableAreas and call
UpdateCompositedScrollOffset on the VisualViewport when the offset
changes from the main thread. We need to update the cc::Layer's offset
since we use a change in this offset to determine that a commit is
needed. This is a similar issue to the one fixed in
https://crrev.com/dfe90fdc496af64515756ba1b5970d2760b7314d

Bug: 956579
Change-Id: Ie9854f3df1b7065bc2d021b131ff6a8998a8f59d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1617545
Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#660930}