1756728 - Allow a11y clients to query URL for cached remote documents

Status: RESOLVED FIXED

(Core :: Disability Access APIs, task)

Description

[James Teh [:Jamie]]

MsaaDocAccessible::get_accValue allows Windows clients to get the URL of a local document. While somewhat hacky, screen readers use this to keep state specific to a page; e.g. to preserve the cursor position across loads. We need to implement this for remote documents when the cache is enabled.

Rather than pushing the URL in the a11y cache, I think we should be able to use CanonicalBrowsingContext::GetCurrentURI. This isn't entirely straightforward because we can't currently get the BrowsingContext from a DocAccessibleParent for an in-process iframe, since DocAccessibleParents are associated with a BrowserParent and in-process iframes don't have their own BrowserParent. I think being able to get the BrowsingContext for a DocAccessibleParent could be useful for other things in future anyway.

I think we can deal with that by sending up the browsing context id when we construct the PDocAccessible. DocAccessibleParent can then use that to get the browsing context via BrowsingContext::Get.

Comment 1

[James Teh [:Jamie]]

Attachment: Bug 1756728 part 1: Make it possible to retrieve a BrowsingContext from a DocAccessibleParent.

Previously, even for remote in-process iframes, it was only possible to retrieve the top level BrowsingContext for the remote process by getting the managing BrowserParent.
This makes it possible to get the correct BrowsingContext even for in-process iframes.

Comment 2

[James Teh [:Jamie]]

Attachment: Bug 1756728 part 2: Support retrieving the URL for cached remote documents.

The BrowsingContext already has this information, so we use that instead of redundantly caching it in RemoteAccessible.
This implementation works even when the a11y cache is disabled, so stop using the sync IPDL URL method.
We can't entirely unify the URL method because we don't have a base class for local/remote documents.
However, a method was added in nsAccUtils to unify this as much as possible.

Comment 3

[James Teh [:Jamie]]

Attachment: Bug 1756728 part 3: Remove now unused PDocAccessible::URL.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/94aa863a913a
part 1: Make it possible to retrieve a BrowsingContext from a DocAccessibleParent. r=morgan
https://hg.mozilla.org/integration/autoland/rev/e4d32dca74a5
part 2: Support retrieving the URL for cached remote documents. r=morgan
https://hg.mozilla.org/integration/autoland/rev/1202447f45d7
part 3: Remove now unused PDocAccessible::URL. r=morgan,ipc-reviewers,mccr8

Comment 5

[Marian-Vasile Laza]

https://hg.mozilla.org/mozilla-central/rev/94aa863a913a
https://hg.mozilla.org/mozilla-central/rev/e4d32dca74a5
https://hg.mozilla.org/mozilla-central/rev/1202447f45d7