pdfviewer: track what objects have been used during rendering. It will be the base of reporting unused objects to warn about ineficiencies in pdf generations, tests, and what features are not implemented fully.

Review URL: https://codereview.chromium.org/23601017

git-svn-id: http://skia.googlecode.com/svn/trunk@11100 2bbb7eff-a529-9590-31e7-b0007b416f81
3 files changed