Some details from other bugs related to the extension icons that may be worth considering while looking into this one:
- Bug 1697806 was aiming to also deduplicate extension svg icons, it has a patch attached and signed-off, but unfortunately it has been backed out because it was regressing (see Bug 1697806 comment 9, and/or Bug 1698237 comment 4)
- As part of Bug 1709655 we have updated the extensions category sidebar icon in about:addons (which was supposed to be 20x20 outlined one but it was the 16x16 filled one instead) and to do that we had to remove on remapping that was being done from toolkit/themes/shared/mozapps.inc.mn (See D114884)
While updating allow-dupes.mn for D114884 I briefly double-checked if any of the entries related to the extension.svg, extensionGeneric.svg etc. listed in allow-dupes.mn were not detected as dupes anymore and (quoting from D114884 comment):
it seems that if I remove chrome/toolkit/skin/classic/mozapps/extensions/extension.svg the mach package comment is still happy.
extensionGeneric.svg instead has still to be listed in the allow-dupes.
I think that it is a bit confusing that browser/chrome/browser/content/browser/extension.svg
and chrome/toolkit/skin/classic/mozapps/extensions/extension.svg are not the same icon (the first one is filled, the second one is outlined), but I think that I would leave that to a separate bug.
In the end I decided to don't remove
chrome/toolkit/skin/classic/mozapps/extensions/extension.svg from allow-dupes.mn in Bug 1709655 and leave it for this issue instead, so that along with deduplicating them we can also evaluate if some of those svg files should be renamed to make it easier to recognize how they differ from each other and/or what role they should have in the UI.