Creating framework for drawShadowedPicture
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2146073003

Committed: https://skia.googlesource.com/skia/+/0ae097d116f4332be02a135ffc99c162473dee6a
Committed: https://skia.googlesource.com/skia/+/95302da19d8b0a3bcd9d9be0e79f486760787f09
Review-Url: https://codereview.chromium.org/2146073003
3 files changed