a11y/Mac: Add screenreader support for SubtleNotificationView announcements.

chrome/browser/ui/views/exclusive_access_bubble_views.cc

Index: chrome/browser/ui/views/exclusive_access_bubble_views.cc
diff --git a/chrome/browser/ui/views/exclusive_access_bubble_views.cc b/chrome/browser/ui/views/exclusive_access_bubble_views.cc
index b67c9378e3143485cdbf322024e9a3a57890a220..f356a4412c188ee2ec6a0d953e3df19f6da31994 100644
--- a/chrome/browser/ui/views/exclusive_access_bubble_views.cc
+++ b/chrome/browser/ui/views/exclusive_access_bubble_views.cc
@@ -85,6 +85,8 @@ ExclusiveAccessBubbleViews::ExclusiveAccessBubbleViews(
                          ->fullscreen_controller()));
 
   UpdateMouseWatcher();
+
+  view_->NotifyAccessibilityEvent(ui::AX_EVENT_ALERT, true);

[tapted, 2016/06/22 00:23:38]

should this be in ExclusiveAccessBubbleViews::Show()? I see matt had it here in
his earlier CL though, so he might have had a reason for that.

[Matt Giuca, 2016/06/22 02:59:20]

Yeah I think it should be in Show(), not the constructor.

[Patti Lor, 2016/06/23 01:00:38]

Done.

 }
 
 ExclusiveAccessBubbleViews::~ExclusiveAccessBubbleViews() {
@@ -125,6 +127,8 @@ void ExclusiveAccessBubbleViews::UpdateContent(
   StopWatchingMouse();
 
   UpdateMouseWatcher();
+
+  view_->NotifyAccessibilityEvent(ui::AX_EVENT_TEXT_CHANGED, true);

[tapted, 2016/06/22 00:23:38]

If we start by fixing Mac and address other platforms in a follow-up, we
shouldn't add this yet (since it's not plumbed through on mac).

[Matt Giuca, 2016/06/22 02:59:20]

Are you saying this code is only relevant on non-Mac platforms? Does it work on
non-Mac?

This is basically what I had in my CL:
https://codereview.chromium.org/1578293003/
which didn't end up reading out the text when the bubble opens, or only did in
some cases IIRC. If this CL is about getting it working on Mac only then we
shouldn't have code that isn't required on Mac.

[Patti Lor, 2016/06/23 01:00:38]

Agreed - as far as I can tell, it doesn't work on other platforms, but I wanted
to get clarification on this because the email thread you forwarded me seems to
suggest that adding this particular line works for dmazzoni.

[Matt Giuca, 2016/06/24 04:21:12]

I'm not sure (it's really hard to test on other platforms because I don't have
any voice modules installed). I think if this isn't necessary for Mac we should
just take it out of this CL.

[dmazzoni, 2016/06/24 05:26:03]

This is a reasonable event to fire on any platform when static text changes. I'd
leave it in.

Note that this would not typically cause the text to be announced.

In general, only AX_EVENT_ALERT means to immediately announce something.
Any other event is informative - it allows a client to know that something
changed
so that it can update its internal cache. If the object is currently focused I
would
expect it to announce - so an event fired on an editable text control or
checkbox
would be announced immediately, for example, when focused. Hope that helps.

[Patti Lor, 2016/06/27 05:10:38]

Ended up plumbing ui::AX_EVENT_TEXT_CHANGED through for Mac as it was quite
simple, so have left this line in. What dmazzoni@ said is also true though (as
in, having this here won't cause the updated text to be announced again) so I
have added a second notification for ui::AX_EVENT_ALERT here as well.

 }
 
 void ExclusiveAccessBubbleViews::RepositionIfVisible() {