commit a2123b3d800a41b180e75398b3e3c91a00a6d508
author Nektarios Paisios <nektar@chromium.org> Mon Aug 16 12:31:57 2021
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Mon Aug 16 12:31:57 2021
tree 0c13896716134ac1b6884b6782531efc3c47131a
parent 60fd59622b22fd58dc9fa5df296126736c279bec

Adds a predicate for finding empty paragraphs and uses it for defining a new paragraph boundary for UIA

In AXPosition, we add a new predicate that defines the "empty paragraph" and we then use this in order to
be able to skip all trailing empty paragraphs that come after a non-empty paragraph.
This is because according to the Microsoft developer documentation, for UI Automation, all trailing empty lines should be merged with the previous paragraph
when searching for the next paragraph.


Meanwhile, this patch makes certain necessary parallel fixes:

1. If two lines or two paragraphs are separated by multiple line / paragraph boundaries that are ignored in the
accessibility tree, treat them as one. This could happen when multiple consecutive
boundaries are hidden via aria-hidden.

2. If the next / previous boundary is requested while on an ignored node, skip to the next / previous unignored
node, so as not to prematurely stop searching for the next / previous boundary:
<div>Paragraph 1</div>
<div aria-hidden="true">Ignored paragraph</div>
<div>Paragraph 2</div>
If we are searching for the previous paragraph start boundary while being on "Paragraph 2", if we don't skip the
"Ignored paragraph" we will prematurely stop there, and would then adjust to the next unignored position, therefore returning back
to "Paragraph 2". This is certainly erronious.
Similar issues arise for format and line boundaries, in addition to paragraph ones.

Lastly, this patch modifies a few comments that describe the various line / paragraph predicates to explain their behavior better.

Split out from:
https://chromium-review.googlesource.com/c/chromium/src/+/3001275/

R=dmazzoni@chromium.org

AX-Relnotes: n/a.
Change-Id: I88335ab06b56cfd6d4f55adc62fb8c05b29652c7
Bug: 1135589, 1147543, 1027753, 1015408
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3063058
Commit-Queue: Nektarios Paisios <nektar@chromium.org>
Auto-Submit: Nektarios Paisios <nektar@chromium.org>
Reviewed-by: Adam Ettenberger <Adam.Ettenberger@microsoft.com>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#912135}