1232648 - Flipping toolkit.telemetry.enabled doesn't allow to turn Experiments back on

Status: RESOLVED FIXED

(Toolkit :: Telemetry, defect, P4)

Description

[Alessio Placitelli [:Dexter]]

We are supposed to disable Experiments if Telemetry is disabled. This works just fine, turning "toolkit.telemetry.enabled" off disables Experiments.
But they cannot be turned back on if you flip the preference to true again.

STR:

- Start Firefox with experiments.enabled and toolkit.telemetry.enabled to true
- Turn toolkit.telemetry.enabled to false
- Experiments will now be disabled
- Turn toolkit.telemetry.enabled to true
- Experiments will not be enabled

That's because in [0] we should pass the state of the "experiments.enabled" pref, not gExperimentsEnabled.
That's what we do when flipping "experiments.enabled", since Preferences.observe passes the value of the changed preference as a parameter to the callback function.

[0] - https://dxr.mozilla.org/mozilla-central/rev/ae37fdb042c07c0cb9d0afcd41372a96454f4f4f/browser/experiments/Experiments.jsm#600
[1] - https://dxr.mozilla.org/mozilla-central/rev/ae37fdb042c07c0cb9d0afcd41372a96454f4f4f/browser/experiments/Experiments.jsm#397

Comment 1

[Mark Banner (:standard8)]

I'm fixing this as part of bug 1348097.

Comment 2

[Georg Fritzsche [:gfritzsche]]

Is that a blocking problem?
Usually flipping that pref is rare, so i'm not sure if we need to invest time in fixing it.

Comment 3

[Mark Banner (:standard8)]

(In reply to Georg Fritzsche [:gfritzsche] [away Apr 13 - 18] from comment #2)
> Is that a blocking problem?
> Usually flipping that pref is rare, so i'm not sure if we need to invest
> time in fixing it.

It was part of a series of issues causing an obscure intermittent failure due to a different test toggling the telemetry preference. Fixing this specific part as part of that was a one-line change with two lines of test case.

Comment 4

[Mark Banner (:standard8)]

Fixed by bug 1348097.