Summary:
Use the application key window bounds if possible.
In the case where the application is not using the entire screen,
like in Split View on an iPad, the running application is
not using the entire screen thus the snapshot stretches to
fill the screen size which is incorrect.
Reviewed By: LukeDefeo
Differential Revision: D47793033
fbshipit-source-id: d6c7932d35bad13752713772d078f94bad530b09
aba50889f2