Fake Sync implementation in ios_web_view_shell.

Change-Id: I6187c15d04b5c1df5d3fc520a2647b2499d2720c
Reviewed-on: https://chromium-review.googlesource.com/c/1345711
Commit-Queue: Hiroshi Ichikawa <ichikawa@chromium.org>
Reviewed-by: John Wu <jzw@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610311}
4 files changed