Minimal changes for SampleApp to eb HiDPI aware on Mac.

R=caryclark@google.com

Review URL: https://codereview.chromium.org/18055009

git-svn-id: http://skia.googlecode.com/svn/trunk@9807 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed