SkPDF: smarter Jpeg when libjpeg-turbo is present

The fallback code does not parse the color type for EXIF-only jpegs.
Since these exist in the wild, we need to find out if they are really
standard YUV or greyscale Jpegs and embed them in PDFs if they are.

BUG=chromium:801430
Change-Id: I93eaf8b8fc22b7169b2fce9520e022b72ad0bf81
Reviewed-on: https://skia-review.googlesource.com/118992
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
6 files changed