Fix recursive GPU processing for SkImageFilter.  Plumb through the
SkImageFilter::Proxy parameter to the GPU recursion path.  Extract
DeviceImageFilterProxy from SkCanvas.cpp into its own .h, and rename it.

https://codereview.appspot.com/6575059/



git-svn-id: http://skia.googlecode.com/svn/trunk@5720 2bbb7eff-a529-9590-31e7-b0007b416f81
14 files changed