Revert "Revert "Add image_diff from the chromium repo.""

This reverts commit 79d76b3da8f72ca3affaaaf2821b1d0bb212f522.

The BUILD.gn file needed a dep to //build/config/sanitizers:deps
in order to link under the asan build.

TBR=blundell@chromium.org

Review URL: https://codereview.chromium.org/804563002