Fixed aspect ratio in cardboard mode.
Fixed aspect ratio in cardboard mode.

The two windows in cardboard mode were incorrectly using the aspect
ratio from when the game started, leading to odd x/y distortion.

This change also allows the game to maintain correct aspect ratio
even if the window is resized while running.

Change-Id: I52e7f1ea441dcf007a27052134e3358953415505

google/zooshi,google/zooshi,google/zooshi,google/zooshi,google/zooshi