Firefox's remote toolbox exposes an editable URL field for tab
descriptors. Submitting that field sends navigateTo to the tab
descriptor rather than the frame target.
Handle the request in the tab actor, route it through the DevTools
delegate, and reuse WebView's URL sanitizing and load path. Add protocol
coverage so the toolbar navigation request stays wired up.
Firefox's inspector toolbar sends goBack and goForward requests to the
tab descriptor when the descriptor advertises navigation support. Thread
those requests through the DevTools delegate and reuse the existing
WebView session-history traversal path.
Keep the legacy frame-target requests working too, matching Firefox's
window-global target compatibility surface. Add protocol coverage for
both entry points so the advertised trait and deltas stay locked down.
Firefox reloads remote targets through the tab descriptor's
reloadDescriptor request. We advertised support for that request, but
left it unhandled, so Firefox could clear inspector state without
causing Ladybird to reload the page.
Route reloadDescriptor, and the legacy frame target reload request,
through the DevTools delegate to WebView's reload path. This lets the
existing navigation notifications publish the replacement inspector root
after the reload completes.
Firefox keeps using the same walker after navigation and expects it to
publish the new document root.
Normal tab debugging also relies on target switching. Re-inspect the tab
when navigation finishes, replace the walker DOM data, and notify the
watcher that the previous top-level frame target was destroyed before a
fresh target becomes available.
Send target availability as a watcher event, not as the watchTargets
response, and give each navigation a new inner window id so Firefox can
associate the new target with the new document.
We must reply to requests received from the client in the order they are
received. The wrench in this requirement is handling requests that must
be performed asynchronously, such as fetching the serialized DOM tree
from the WebContent process.
We currently handle this with a "block token". Async request handlers
hold a token that blocks any subsequent responses from being sent. When
that token is removed (i.e. the async request now has a response to be
sent), the async response is then sent followed by the blocked responses
in-order.
This strategy had a limitation that we could not handle an actor trying
to take 2 block tokens, meaning only one async request could be handled
at a time. This has been fine so far, but an upcoming feature (style
sheet sources) will break this limitation. The client will request N
sources at a time, which would try to take N block tokens.
The new strategy is to assign all requests an ID, and store a list of
request IDs that are awaiting a response. When the server wants to send
a reply, we match the ID of the replied-to message to this list of IDs.
If it is not the first in this list, then we are blocked waiting for an
earlier reply, and just store the response. When the earlier request(s)
receive their response, we can then send out all blocked replies (up to
the next request that has not yet received a response).
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.
The "from" field is required in every response. It is the name of the
actor sending the message. This patch fills in the "from" field in the
Actor base class so that subclasses don't have to.
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.
Previously, we could connect to our DevTools server from Firefox, but
could not see any information on Ladybird's opened tabs. This implements
enough of the protocol to see a tab list, but we cannot yet inspect the
tabs.
