Revert "disable passing discards through GrIODB."

This reverts commit 3cdd1460991b723521be8b7c26e808e640402b7e.

The original CL was landed only to do an experimental DEPS roll to Chromium.

BUG=skia:

Review URL: https://codereview.chromium.org/219023008

git-svn-id: http://skia.googlecode.com/svn/trunk@13995 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed