Add input/output image logging to processor tests

Moves SkBitmap to base64 uri code into test utils

Bug: skia:
Change-Id: I4f92761fd2e643c38ed00a200b1cb62778a85948
Reviewed-on: https://skia-review.googlesource.com/158340
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
4 files changed