User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.119 Safari/537.36

Steps to reproduce:

1. Install attached extension, opened the background console for it.

Actual results:

The following was logged:

onChanged example: { oldValue: undefined, newValue: false } local

Expected results:

The following should be logged:

onChanged example: { oldValue: undefined, newValue: false } local
onChanged example: { oldValue: false } local

The event works as expected on both older versions of Firefox and Chrome:

Firefox 64.0 (64-bit)

onChanged example: { oldValue: undefined, newValue: false } local
onChanged example: { oldValue: false } local

Chrome 72.0.3626.119

onChanged example: { newValue: false } local
onChanged example: { oldValue: false } local

See also the related discussion on the Adblock Plus issue tracker: https://issues.adblockplus.org/ticket/7430

(Should I mark issues like this as blocking #467520 or #1226547?)

https://hg.mozilla.org/mozilla-central/rev/176a8c9d1b7b

Let's QA verify the fix as applied in Nightly using the STR from comment 0.

Comment on attachment 9055516 [details]
Bug 1541449 - storage.local API should fire onChanged event when falsey values are removed. r?mixedpuppy!

Beta/Release Uplift Approval Request

• Feature/Bug causing the regression: Bug 1488825
• User impact if declined: Some extension may not behave as expected because the expected onChanged event is not being fired when the changed item has a falsey value (e.g. as mentioned in comment 1, AdBlock Plus doesn't update part of its UI because the expected onChanged event has not been fired).
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: No
• Needs manual test from QE?: Yes
• If yes, steps to reproduce: QA verification of the fix can be done using the STR provided by the reporter in comment 0.
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): The change required to fix the issue is small and restricted to the internal function that implements the underlying behavior for the storage.local.remove API method.
  The change also includes additional test cases to ensure that this scenario is explicitly tested as part of the automated tests.
• String changes made/needed:

I'll take it in Beta once QA has verified it in Nightly, thanks for the STR!

I’ve reproduce this issue following the steps from comment 0 with Fx 68.0a1(2019-04-03) on Ubuntu 18.04 x64.
The issue is verified fixed with Fx 68.0a1 (2019-04-10) on Ubuntu 18.04 x64, macOS 10.13 and Windows 10 x64.

Comment on attachment 9055516 [details]
Bug 1541449 - storage.local API should fire onChanged event when falsey values are removed. r?mixedpuppy!

Impacts some high volume extensions, has tests and was veirfied by QA po Nightly, uplift approved for 67 beta 11, thanks!

https://hg.mozilla.org/releases/mozilla-beta/rev/8f56f6681da4

Comment on attachment 9055516 [details]
Bug 1541449 - storage.local API should fire onChanged event when falsey values are removed. r?mixedpuppy!

Beta/Release Uplift Approval Request

• Feature/Bug causing the regression: Bug 1488825
• User impact if declined: Same as comment 7
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: Yes
• If yes, steps to reproduce: QA verification of the fix can be done using the STR provided by the reporter in comment 0.
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Same as comment 7
• String changes made/needed:

So far, we don't have another dot release planned, but I'll keep this open for another week in case something else crops up.

Comment on attachment 9055516 [details]
Bug 1541449 - storage.local API should fire onChanged event when falsey values are removed. r?mixedpuppy!

We're a week or so out from 67 release. Wontfix for 66.