Adding API to SkGPipe and SkDeferredCanvas for controlling memory usage externally

BUG=http://code.google.com/p/chromium/issues/detail?id=136828
Review URL: https://codereview.appspot.com/6454102

git-svn-id: http://skia.googlecode.com/svn/trunk@4971 2bbb7eff-a529-9590-31e7-b0007b416f81
5 files changed