Migrate WebContentsCreatedCallback to BindOnce

Bug: 714018
Change-Id: If45e105f525c6133fcf81b66ab8c9072d5514815
Reviewed-on: https://chromium-review.googlesource.com/1085229
Commit-Queue: Mark Pilgrim <pilgrim@chromium.org>
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564482}
18 files changed