commit cd778184be715a31314427f55b1fe43096641bf0
author Xianzhu Wang <wangxianzhu@chromium.org> Thu Jun 04 21:48:41 2020
committer Commit Bot <commit-bot@chromium.org> Thu Jun 04 21:48:41 2020
tree 4cbe6ef7c060c9fcb5098fb81c128f055a47022d
parent 5b2b4b0c92a90ab92536897bfa5f0e06350d2865

Reland "Fix layer/phase violation of custom scrollbar painting"

This reverts commit 94c64b41dd5211b67014b2862037ae411ad35cda.

After the revert, we no longer have crbug.com/1086968 crashes.
The root cause of the crash is still unclear, but crrev.com/c/2226924
changed the class hierarchy of LayoutCustomScrollbarPart which may
affect the issue. Reland the CL tentatively to see if the crash still
occurs.

Original change's description:
> Revert "Fix layer/phase violation of custom scrollbar painting"
> 
> This reverts commit 64bcb13df246ce5034a940715b39c53c0fd33794.
> 
> Reason for revert: Tentative for crbug.com/1086968.
> 
> Original change's description:
> > Fix layer/phase violation of custom scrollbar painting
> > 
> > TL;DR, with this CL:
> > - We no longer update custom scrollbar part position during paint;
> > - We avoid unnecessary ScheduleAnimation when painting custom
> >   scrollbars;
> > - CustomScrollbar::*Rect() methods no longer have side effects;
> > - Some FIXMEs are fixed.
> > 
> > Details:
> > 
> > Previously LayoutCustomScrollbarPart::FrameRect() stored different
> > values at different document lifecycle stages:
> > 
> > - Before paint, its location was always zero, and the size was not the
> > actual size for some parts, but the minimum size calculated from the
> > style, not based on layout, though updated in UpdateLayout().
> > UpdateLayout() was called not during layout (as a scrollbar part is
> > not in the layout tree), but anytime we wanted the minimum size from
> > const methods of CustomScrollbar.
> > 
> > - During paint, as the FrameRect() calculated during UpdateLayout was
> > not the real frame rect, we updated the frame rect to make sure they
> > would be painted correctly. This caused unnecessary
> > SetShouldCheckForPaintInvalidation when the FrameRect changed and
> > unnecessary ScheduleAnimation().
> > 
> > This CL contains the following changes:
> > - Removes LayoutCustomScrollbarPart::UpdateLayout().
> >   Adds ComputeThickness() and ComputeLength(), and lets Margin*() get
> >   style directly, to replace the original UpdateLayout() (which called
> >   SetSize()/SetMargin*()) + Size()/Margin*() in the const methods of
> >   CustomScrollbar. This removes the dependency of the const methods
> >   on the temporary incorrect FrameRect().
> > 
> > - Adds CustomScrollbar::PositionScrollbarParts() to set the correct
> >   FrameRect() for scrollbar parts. It's called from several places that
> >   position of scrollbar parts can change. This replaces the Set* called
> >   from CustomScrollbarTheme::Paint*.
> > 
> > Bug: 856802
> > Change-Id: I5b120294a31a7f91831441cb361adfd27aefa44e
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2167602
> > Reviewed-by: Philip Rogers <pdr@chromium.org>
> > Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#771890}
> 
> TBR=wangxianzhu@chromium.org,pdr@chromium.org
> 
> # Not skipping CQ checks because original CL landed > 1 day ago.
> 
> Bug: 856802, 1086968
> Change-Id: If1703dcda1d4cb6a53a132557b34867090f397ae
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2225222
> Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
> Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#773772}

TBR=wangxianzhu@chromium.org,pdr@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 856802, 1086968
Change-Id: I7108a82ed453c32a87ca1aad689cf8a1c157f8fc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2231458
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#775292}