use factories instead of manually setting fields

this allows us to (later) land change in Skia where we add more fields

Review URL: https://codereview.chromium.org/531883002

git-svn-id: svn://svn.chromium.org/blink/trunk@181257 bbb929c8-8fbe-4397-9dbb-9b2b20218538
2 files changed