Merge pull request #14304 from RudyLu/keyboard/Bug930358-use_manifestURL_to_indentify_keyboardApp

Bug 930358 - Use manifestURL instead of app origin to identify a
r=gnarf, gary, arthur(cherry picked from commit 846b677b4975639dc61fce28e21d36d724f38160)
a=timdream

Conflicts:
	shared/resources/keyboard_layouts.json