[ObjC ARC] Converts ios/public/provider/chrome/browser/distribution:test_support to ARC.

Automatically generated ARCMigrate commit
Notable issues:None
BUG=624363
TEST=None

Review-Url: https://codereview.chromium.org/2832493003
Cr-Commit-Position: refs/heads/master@{#465922}
2 files changed