Plumb in flag for reusing scratch textures

R=bsalomon@google.com, brian@thesalomons.net

Author: robertphillips@google.com

Review URL: https://chromiumcodereview.appspot.com/19636002

git-svn-id: http://skia.googlecode.com/svn/trunk@10170 2bbb7eff-a529-9590-31e7-b0007b416f81
3 files changed