Migrate //content/renderer/dom_storage to OnceCallback

Bug: 714018

Change-Id: I735449654310ff89ecd2f5e7a56a638eb6bf7a28
Reviewed-on: https://chromium-review.googlesource.com/970383
Commit-Queue: Joshua Bell <jsbell@chromium.org>
Reviewed-by: Joshua Bell <jsbell@chromium.org>
Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544910}
5 files changed