commit af21eb5c8c9a699e17d151021e04ccde8d586cce
author Minju Kim <mkim@igalia.com> Wed Apr 17 01:59:59 2024
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed Apr 17 01:59:59 2024
tree 9e3035a0dd9cf11deb361f1024e1b31e3854840b
parent dc389d2cce5d51c25e53b70da6a5f2f9c5cc396b

Introduce GetWebExposedScrollOffsets for scrollingAPIs

We have encountered the issue where simply changing zoom levels
can lead to unexpected scrolling on our sample page.
This is due to updating of truncated scroll offset [1]
when FractionalScrollOffset is disabled, which led to a loss of
fractional precision, resulting in a 1px discrepancy
at the webAPI level.

To ensure compatibility with web standards while preserving the
integrity of scroll offsets, this commit introduces GetWebExposedScrollOffsets
for scrollingAPIs (e.g. Element.scrollTop, Element.scrollLeft,
window.scrollX, window.scrollY).
Also by enabling FractionalScrollOffsets, we can address
underlying issue of scroll offset truncation.

[1] https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/scroll/scrollable_area.cc;drc=43e12b162c85779c8350871dac4b319cc1874f16;l=671

Bug: 326122314

Change-Id: I070be67b0e73d925738d556ff0626e6a1119ff00
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5348560
Commit-Queue: Minju Kim <mkim@igalia.com>
Reviewed-by: David Bokan <bokan@chromium.org>
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Steve Kobes <skobes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1288468}