commit d44db9636279ee5238407ea776dbaab82cfd5363
author Xianzhu Wang <wangxianzhu@chromium.org> Fri Aug 31 23:08:16 2018
committer Xianzhu Wang <wangxianzhu@chromium.org> Fri Aug 31 23:08:16 2018
tree 722719828f8ba48d1a7a08aa088dcda0ac3f8d11
parent 542c2443219618f7aee27f2ff28029af82180819

[PE] Fix LayoutBox Client/Padding/Content boxes with scrollbars (especially vertical-rl)

This CL tries to correct the box model when there are scrollbars,
especially in vertical-rl mode. According to
https://www.w3.org/TR/css-overflow-3/#scrollbar-layout, scrollbars
"should be inserted between the inner border edge and the outer
padding edge".

Changes to the previous code:

- Padding|client box now excludes scrollbars, with the help of
  (Top|Left|Bottom|Right)ScrollbarWidth methods which can get the
  scrollbar widths in physical directions in various writing modes.

- Content box is now based on the new padding box by excluding the
  paddings.

- Layout of contents is now based on the correct box model. In
  vertical-rl mode, layout of contents in blocks direction starts
  from the inner edge of the new content box which has been properly
  adjusted for the scrollbar.

- Now LayoutBox::Location() and Location::PhysicalLocation() in the
  initial scroll state are correct in all writing-modes. Previously
  when they were incorrect in vertical-rl mode and some flex box
  directions, requiring an artificial scroll offset to paint the
  content at correct place.

- With the correct padding box, content box, Location(),
  PhysicalLocation(), we no longer need the band-aid code to create the
  correct painted result.

The changed code is mostly in LegacyLayout code. Some changed code is
in LayoutNG that previously converted correct LayoutNG geometries into
the problematic geometries that were previously expected by
LegacyLayout.

The correct box model is required by blink-gen-property-trees because
we can't band-aid the incorrect results in paint properties after
painting.

Bug: 833167,853945,858843,878809,876266

Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;luci.chromium.try:linux-blink-gen-property-trees;luci.chromium.try:linux_layout_tests_layout_ng;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I41faf1ca0bfb95cb287c72703f08c8bd44e9e752
Reviewed-on: https://chromium-review.googlesource.com/1185901
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Reviewed-by: Christian Biesinger <cbiesinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#588201}