add readPixels to SkSurface (later try to remove it from SkCanvas)

BUG=skia:
TBR=bsalomon, robertphilips

Review URL: https://codereview.chromium.org/789993002
Update SKP version

Automatic commit by the RecreateSKPs bot.

TBR=

Review URL: https://codereview.chromium.org/760943003