1701004 - DevTools eye dropper command should use a dedicated descriptor & target

Status: RESOLVED FIXED

(DevTools :: General, task, P3)

Description

[Julian Descottes [:jdescottes]]

See https://phabricator.services.mozilla.com/D109470#inline-613143

In order to pick a color on the page, the eyedropper tool can create a TabDescriptor + inspector front early: https://searchfox.org/mozilla-central/rev/6c9ff2820d3aae683ec87c53c79e5108d54f3f76/devtools/client/menus.js#133-139

      const descriptor = await TabDescriptorFactory.createDescriptorForTab(
        window.gBrowser.selectedTab
      );
      const target = await descriptor.getTarget();
      await target.attach();
      const inspectorFront = await target.getFront("inspector");

Since the tab descriptor is cached per tab in the TabDescriptorFactory, this descriptor & front will be reused if you open a toolbox afterwards.

This is confusing and fragile. The eyedropper should not rely on the cache of descriptors which is really intended for toolboxes.

This might get fixed indirectly by Bug 1700909 when we move the descriptor (or rather commands) caching to gDevTools.

Comment 1

[Alexandre Poirot [:ochameau]]

Note that I think that bug 1700909 doesn't have to be a blocker.
We can probably migrate from TabDescriptorFactory to CommandsFactory and it should address target switching issues.

Comment 2

[Julian Descottes [:jdescottes]]

Adding some easy STRs to reproduce the bug here:

• open https://www.mozilla.org/en-US/
• start the eyedropper (Tools > Browser Tools > Eyedropper)
• close the eyedropper
• open the toolbox
• select the body in the inspector

ER: The ruleview should show a rule for body pointing to protocol-mozilla.66302a5234e3.css (you might see a different hash)
AR: The ruleview shows "inline" for all rules

This is because the toolbox will reuse a cached Front created without watcher support (https://searchfox.org/mozilla-central/rev/b7bc94b4689a7f002c61d016c6e162e5e5708bf3/devtools/client/fronts/inspector.js#58-67).

Comment 3

[Julian Descottes [:jdescottes]]

Attachment: Bug 1701004 - [devtools] Use a dedicated commands instance for the eyedropper menu item

Depends on D119170

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/54a777ac91e3
[devtools] Use a dedicated commands instance for the eyedropper menu item r=nchevobbe

Comment 5

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/54a777ac91e3