300864 - Regression: page load errors are no longer accessible

Status: RESOLVED FIXED

(Firefox :: Disability Access, defect)

Description

[Aaron Leventhal]

In the past page load errors brought up a modal dialog, which was accessible
with a screen reader.

After the checkin for bug 282050, these became "XUL error pages". There is
notification sent to a screen reader that these error pages are ready to read,
because the typical web progress listener STATE_STOP event does not occur for them.

Comment 1

[Aaron Leventhal]

Things are breaking because of the PageHide event that is fired when the XUL
error page comes up.

So I was wrong in the original summary. We receive a STATE_STOP progress
listener notification when the XUL error page comes up, but we also receive
PageHide right after that, which makes us destroy the current document accessible.

Not sure how we should know that the current PageHide should be ignored because
there is an error page there.

Comment 2

[Aaron Leventhal]

Attachment: 1) Use START_START instead of STATE_TRANSFERRING (which may not be fired if page not found), 2) Only destroy accessible document for "unload" not "PageHide"

It seems okay to keep around the accessible cache for a document that's cached.
Doing so gets around the problem of the document being destroyed because of the
PageHide that occurs when a XUL error page is shown.

Comment 3

[Mike Kaply [:mkaply]]

Comment on attachment 189380 [details] [diff] [review]
1) Use START_START instead of STATE_TRANSFERRING (which may not be fired if page not found), 2) Only destroy accessible document for "unload" not "PageHide"

a=mkaply

Comment 4

[Aaron Leventhal]

Checking in nsAccessibilityService.cpp;
/cvsroot/mozilla/accessible/src/base/nsAccessibilityService.cpp,v  <-- 
nsAccessibilityService.cpp
new revision: 1.147; previous revision: 1.146
done
Checking in nsRootAccessible.cpp;
/cvsroot/mozilla/accessible/src/base/nsRootAccessible.cpp,v  <-- 
nsRootAccessible.cpp
new revision: 1.125; previous revision: 1.124
done

Comment 5

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

This patch caused a *massive* leak -- i.e., we basically don't free at least a significant portion of content nodes until shutdown when the system accessibility preference is enabled.  (This means we also leak raw image data, which is huge.)  See bug 330624.

Comment 6

[Firefox Bug Husbandry Bot]

https://bugzilla.mozilla.org/show_bug.cgi?id=1527381