Prefer native scaling to sampling

Prefer native scaling to sampling

In the cases we have come across so far, native scaling has better performance
and correctness than sampling.  If native scaling is supported we want to use
it.

Jpegs native scale rounds up.
Ex: An 11x11 image with sampleSize=8 scales to 2x2.

SkScaledCodec rounds down.
Ex: An 11x11 image with sampleSize=8 scales to 1x1.

Before the CL, we would choose to use SkScaledCodec because it scales closer to
the "ideal" scale.

I think we want to go with the native option as long as its within 1 of the
ideal value.
BUG=skia:

Review URL: https://codereview.chromium.org/1284243004