[Android] Display no scaled image when no border specified in LaunchScreen

When no border specified in the manifest, the image should not be scaled, just display
the image centered in the screen.

BUG=XWALK-1998
(cherry picked from commit b51e1af3fca89d4ba7f8b909bce2ea5013c5dd57)
Merge pull request #2182 from kurli/crssswalk-7

[Android] Display no scaled image when no border specified in LaunchScre...