MacViews: Fix accessibility hit tests, provide AXTitle

MacViews: Fix accessibility hit tests, provide AXTitle

The NSView hosting composited UI was stealing hit tests used for
accessibility. This CL makes the compositor superview unhittable.

An integration test is added. Implement [AXPlatformNodeCocoa AXTitle]
which is needed anyway and gives the test something to check for.

BUG=462133
Committed: https://crrev.com/a78caa3b90acc4d5d33f905f9cae774d9605d029
Cr-Commit-Position: refs/heads/master@{#319595}

[tapted, 2015-03-06 06:30:01]

tapted@chromium.org changed reviewers:
+ andresantoso@chromium.org, dmazzoni@chromium.org

[tapted, 2015-03-06 06:30:02]

Hi Andre and Dominic please take a look

[dmazzoni, 2015-03-06 07:58:01]

lgtm

Code and test looks great, one completely optional suggestion.

https://codereview.chromium.org/976403004/diff/1/ui/accessibility/platform/ax...
File ui/accessibility/platform/ax_platform_node_mac.mm (right):

https://codereview.chromium.org/976403004/diff/1/ui/accessibility/platform/ax...
ui/accessibility/platform/ax_platform_node_mac.mm:280: // Always add title.
Cocoa asks for it regardless of it appearing in here,
Rather than a comment for "title", I'd maybe just put a comment at the top
saying "these attributes are required on all accessibility objects" - later
we'll add more below that are optional.

[tapted, 2015-03-06 10:51:16]

Patchset #2 (id:20001) has been deleted

[tapted, 2015-03-06 10:53:05]

Patchset #2 (id:40001) has been deleted

[tapted, 2015-03-06 11:01:18]

https://codereview.chromium.org/976403004/diff/1/ui/accessibility/platform/ax...
File ui/accessibility/platform/ax_platform_node_mac.mm (right):

https://codereview.chromium.org/976403004/diff/1/ui/accessibility/platform/ax...
ui/accessibility/platform/ax_platform_node_mac.mm:280: // Always add title.
Cocoa asks for it regardless of it appearing in here,
On 2015/03/06 07:58:01, dmazzoni wrote:
> Rather than a comment for "title", I'd maybe just put a comment at the top
> saying "these attributes are required on all accessibility objects" - later
> we'll add more below that are optional.

Done. Added the comment at top.

The comment on Title didn't really capture what was "weird" about what Cocoa was
doing, so I've updated it to say "Title is required for most elements. Cocoa
asks for the value even if it is omitted here, but won't present it to
accessibility APIs without this."

I think we could just add it optionally too after checking
node_->HasStringAttribute(ui::AX_ATTR_NAME) and everything would still work
fine. (And maybe that's better -- happy to change it). But it felt inconsistent
to unconditionally give an answer to AXTitle, and plenty of Apple's own UI seems
to do it this way (i.e. present the attribute name, but return <nil> if there's
nothing appropriate).

Either way, easy to move down to the optional segment when this is fleshed out
more :)

[Andre, 2015-03-06 18:00:54]

LGTM

[tapted, 2015-03-06 22:48:01]

The CQ bit was checked by tapted@chromium.org

[tapted, 2015-03-06 22:48:01]

The patchset sent to the CQ was uploaded after l-g-t-m from
dmazzoni@chromium.org
Link to the patchset: https://codereview.chromium.org/976403004/revert#ps80001
(title: "tweak comments")

[commit-bot: I haz the power, 2015-03-06 22:49:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/976403004/80001

[commit-bot: I haz the power, 2015-03-07 00:52:26]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-03-07 00:52:28]

Try jobs failed on following builders:
  mac_chromium_compile_dbg_ng on tryserver.chromium.mac (JOB_TIMED_OUT, no build
URL)
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_TIMED_OUT, no build URL)
Timed out jobs are not retried to avoid causing additional load on the builders
with large pending queues.

[tapted, 2015-03-07 04:51:55]

The CQ bit was checked by tapted@chromium.org

[commit-bot: I haz the power, 2015-03-07 04:52:57]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/976403004/80001

[commit-bot: I haz the power, 2015-03-07 06:53:37]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-03-07 06:53:39]

Try jobs failed on following builders:
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_TIMED_OUT, no build URL)
Timed out jobs are not retried to avoid causing additional load on the builders
with large pending queues.

[tapted, 2015-03-08 14:33:54]

The CQ bit was checked by tapted@chromium.org

[commit-bot: I haz the power, 2015-03-08 14:34:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/976403004/80001

[commit-bot: I haz the power, 2015-03-08 17:29:47]

Committed patchset #3 (id:80001)

[commit-bot: I haz the power, 2015-03-08 17:30:12]

Patchset 3 (id:??) landed as
https://crrev.com/a78caa3b90acc4d5d33f905f9cae774d9605d029
Cr-Commit-Position: refs/heads/master@{#319595}