add peekPixels to SkCanvas and SkSurface

fix reference to SkBaseDevice, which was only a problem in no-gpu build

This reverts commit 4fa44a6bf73891b21917fb90d02beef9143bffa3.

R=reed@google.com

Author: reed@chromium.org

Review URL: https://codereview.chromium.org/163603003

git-svn-id: http://skia.googlecode.com/svn/trunk@13432 2bbb7eff-a529-9590-31e7-b0007b416f81
36 files changed