SamplePicture no longer uses SkImageRef

Motivation: in an attempt to simplify life, we are depricating
SkImageRef and its subclasses.  To that end, SamplePicture will now
use SkDiscardablePixelRef.

Also, fixed missing resource.

BUG=
R=scroggo@google.com

Review URL: https://codereview.chromium.org/116423006

git-svn-id: http://skia.googlecode.com/svn/trunk@12737 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed