SkImage_Generator::onMakeColorSpace avoid 565

I forgot that if a png has the significant bit
chunk set to R=5, G=6, B=5, we will recommend
a decode to 565.

We need to avoid this.  The codec does not
support color correct 565.

BUG=skia:

Change-Id: Ieb74bfaf100504d9748e4b8014a8a4e425428c7a
Reviewed-on: https://skia-review.googlesource.com/10166
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Matt Sarett <msarett@google.com>
1 file changed