manifest: Use browser_specific_settings for Firefox/Chrome compatibility

[liskin]

Since Firefox 48, it's possible to use browser_specific_settings instead
of applications. This way, the manifest works without modification
across most browsers.

It's also the correct key according to webextensions draft:
https://browserext.github.io/browserext/#dfn-browserspecificsettings

[erichgoldman]

I don't think that Chrome respects this value:

• https://stackoverflow.com/questions/56271601/chrome-extensions-do-not-respect-browser-specific-settings
• https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/browser_specific_settings#Browser_compatibility

I upload separate versions to Chrome Store and Mozilla. The comment works better for now.

Do you know of this working for Chrome on other extensions?

[liskin]

Yes, Chrome does show a warning, but that warning is harmless. All my extensions (https://github.com/liskin/strava-map-switcher, https://github.com/liskin/empty-tab) use it without any trouble, and I upload the exact same code to both extension stores.

Chrome does not respect the value, but you don't need it to respect it. All you need is for Chrome to ignore it.

[erichgoldman]

While I see the value for testing and some code cleanliness, I don't think I will merge this change. Since I need to deploy separately, the effort to remove the code block is minimal and no warnings are better than warnings which can be ignored. My concern is that Chrome may change its behavior in the future forcing a quick turn around for an update.

[liskin]

Fair enough. My primary motivation was being able to use your extension in both Chrome and Firefox from one git clone without any modifications, but I can carry local patches with no problem.

[erichgoldman]

I think what I may do is switch to your recommendation and then comment it out or I may leave it in with a comment to remove it for Chrome builds. I need to think about it a bit more.