This is enough for Firefox to display the Accessibility tab, containing
our accessibility tree which can be inspected. Most information is
blank for now.
There's quite a bit of duplication between AccessibilityWalkerActor and
WalkerActor - it might be worth trying to make a base class once the
details are figured out. Frustratingly, the two don't work quite the
same: for a lot of messages that would be sent to WalkerActor, the
accessibility equivalent is sent to the AccessibilityNodeActor instead.
Co-authored-by: Tim Flynn <trflynn89@pm.me>
This is to prepare for an upcoming change where we will need to track
replies to messages by ID. We will be able to add parameters to this
structure without having to edit every single actor subclass header
file.
There is a lot needed all at once to actually inspect a tab's DOM tree.
It begins with requesting a "watcher" from a TabActor. It seems there
can be many types of watchers, but here we implement the "frame" watcher
only. The watcher creates an "inspector", which in turn creates a
"walker", which is the actor ultimately responsible for serializing and
inspecting the DOM tree.
In between all that, the DevTools client will send a handful of other
informational requests. If we do not reply to these, the client will not
move forward with the walker. For example, the CSSPropertiesActor will
be asked for a list of all known CSS properties.
