Move computation of decodeColor- Type and Space

Bug: 70846442
Test: I5110881203c000474116a94a48f2afc9a9b62001

Delay computing decodeColorType until right before we may change it (and
delay reinterpreting the pointer along with it). More interestingly,
defer computing decodeColorSpace until *after* we may have changed the
decodeColorType. Along with a change in Skia, this allows us to match
the color type of inBitmap, as intended.

Change-Id: If0ca4a61d338a13473a96faf900c84010ae46d41