commit ae0e2a6dcdbffb268a26bb531025bd92506bf9ea
author Victor Fei <vicfei@microsoft.com> Wed Jun 03 17:34:55 2020
committer Commit Bot <commit-bot@chromium.org> Wed Jun 03 17:34:55 2020
tree 09ba484f1bccfed9e83cdd696f21ce6661bc4774
parent d9ab1e4797336f691e7303f4353a3b2f598e3ccf

Fix for ISelectionItemProvider::Select on focused element

The motivation behind this change is that for content like below,
Windows Narrator cannot trigger the links in the tabs.
  <div role="tablist">
    <a href="https://twitter.com" role="tab">tab1</a>
    <a href="https://wikipedia.org" role="tab">tab2</a>
    <a href="https://w3.org" role="tab">tab3</a>
  </div>
This is because for single-selection container we have the behavior
that selection follows focus.
https://www.w3.org/TR/wai-aria-practices-1.1/#kbd_selection_follows_focus
In Item Navigation, Narrator sets focus first to the tab, but upon
focus the a11y selected state is set to true. When Narrator attempts
to perform ISelectionItemProvider::Select (Enter) on the tab to
trigger the link, no action would occur because the selected state is
already set to true.

This CL fixes UIA::ISelectionItemProvider::Select() to still
perform action::kDoDefault if the element is already selected due to
focus. Previously, if an element is already selected, for any reason,
Select() would not perform any a11y action.
This CL also introduces ax::mojom::BoolAttribute::kSelectedFromFocus
and uses it to communicate between renderer process and browser
process that an element is selected due to it being focused.
This CL should not affect ISelectionItemProvider::Select()
behavior on multiselectable containers.

AX-Relnotes: Windows Narrator can now trigger default action on an
element in a single-selection container such as a tabitem.

Bug: 847971
Change-Id: I12026b37ed25b867384895eb520eba658aad6f20
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2219155
Reviewed-by: Kevin Babbitt <kbabbitt@microsoft.com>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Victor Fei <vicfei@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#774693}