unify how we handle externally-provided storage in SkWriter32, with the goal
of simplifying the logic in reserve() so it can be inlined/accelerated.
Review URL: https://codereview.appspot.com/6962048

git-svn-id: http://skia.googlecode.com/svn/trunk@6923 2bbb7eff-a529-9590-31e7-b0007b416f81
3 files changed