Hide SkCanvas getDevice() & getTopDevice()}

No longer used externally.

R=reed@google.com

Change-Id: I450148010852c2567d136d2c85c8837c6dcbc6b9
Reviewed-on: https://skia-review.googlesource.com/6974
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
2 files changed