Fix in-page logic for allow_universal_access_from_files.

The previous approach failed if a file URL did a replaceState to another
origin and then back to a file URL.  The new approach checks the frame's
origin instead, which stays as file:// the whole time.

BUG=553418
TEST=See bug comment 11 for repro steps.

Review URL: https://codereview.chromium.org/1457053004

Cr-Commit-Position: refs/heads/master@{#360917}
4 files changed