Urlbar Top Sites Experiment Extension

This is the extension for the urlbar top sites add-on experiment. When installed, focusing Firefox's urlbar automatically opens the urlbar view and shows the top sites from your new-tab page. (Two caveats: The view does not automatically open when the current tab is the new-tab page itself since it already shows your top sites. It also doesn't open in private windows.)

Bug 1547279 is the meta bug that tracks this experiment.

Requirements

Firefox 69b13 or newer
Either a Mozilla-signed version of the add-on; or Firefox Nightly, Developer Edition, or any other Firefox build that gives privileges to temporarily installed add-ons (Beta does not). This add-on uses Mozilla-privileged APIs (browser.urlbar and browser.normandyAddonStudy)

Running

You can use web-ext or about:debugging. Both will load the add-on as a temporary add-on, so you'll need to use Firefox Nightly, Developer Edition, or any other Firefox build that gives privileges to temporarily installed add-ons.

Building

Use web-ext to build the add-on zip file.

Testing

The tests directory contains a browser chrome mochitest and a head.js. The head.js implements a simple framework for testing Normandy experiment add-on files.

The requirements above for running the add-on apply to testing it, too. You'll need either a Mozilla-signed version of the add-on; or Firefox Nightly, Developer Edition, or any other Firefox build that gives privileges to temporarily installed add-ons.

To run the test in a particular version of Firefox, you'll need to clone the repo from which your Firefox was built. If you're testing in Nightly 70, you'll need mozilla-central. If you're testing in Developer Edition 69 or Beta 69, you'll need mozilla-beta.

Then:

cd into your urlbar-top-sites-experiment clone.
Copy tests/* into srcdir/testing/extensions/, where srcdir is the top-level directory of your Firefox repo:
```
$ cp -R tests/* srcdir/testing/extensions
```
Build the add-on zip file using web-ext as described above:
```
$ web-ext build
```
Or use a signed copy of the zip file.

Copy the zip file into srcdir/testing/extensions/tests/browser:

$ cp web-ext-artifacts/urlbar_top_sites_experiment-1.0.0.zip srcdir/testing/extensions/tests/browser

Update EXPECTED_ADDON_SIGNED_STATE as necessary in srcdir/testing/extensions/tests/browser/browser_urlbarTopSitesExtension.js. If your zip file is unsigned, its value should be AddonManager.SIGNEDSTATE_MISSING. If it's signed, it should be AddonManager.SIGNEDSTATE_PRIVILEGED.
cd into your srcdir.
Run the test using mach:
```
$ ./mach mochitest -f browser --appname <path to Firefox binary> testing/extensions/tests/browser/browser_urlbarTopSitesExtension.js
```
If your Firefox repo itself contains the Firefox binary (because you ran mach build), you can omit the --appname argument.

If mach doesn't find the test, remove your objdir, mach build, and try again from step 1. (There's got to be a better way…)

Linting

This project uses the linting rules from mozilla-central. From your urlbar-top-sites-experiment directory, run: