This is a cautionary move: when uploaded to infrastructure,
background.apk will not look so bad; but browser.apk is likely to
confuse folks. (These files will be in the same directory as
fennec-*apk, and sort earlier than that file.)
I considered including "tests" in the name, but decided not to make a
long name even longer.
This also renames the Android package. This is purely cosmetic, since
the package has no consumers (infrastructure, mach, etc). But this looks
nicer in IDEs: the generated classes fit into the class hierarchy.
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