extract some common code from PictureRenderer

R=borenet@google.com

Author: epoger@google.com

Review URL: https://codereview.chromium.org/273703006

git-svn-id: http://skia.googlecode.com/svn/trunk@14638 2bbb7eff-a529-9590-31e7-b0007b416f81
12 files changed