GitLab

Wrap file path references with "EnsureFileExists()" which acts as a
simple identity function, except for invalid paths for which it
raises IOErrors.

Bug: 837200
Change-Id: Ie718cd5517415b375ed3bf5d5112d59b32074c04
Reviewed-on: https://chromium-review.googlesource.com/1037778Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: Kevin Marshall <kmarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555137}