GitLab

Originally the webview content was always set to clickable but after
http://crrev.com/551479 it wasn't. This CL restores original behaviour.

Also adds a test to ensure this remains true in the future.

Bug: 857427
Change-Id: If7a765f146290b933f57e514f26ad8a672f7695e
Reviewed-on: https://chromium-review.googlesource.com/1127951Reviewed-by: Jinsuk Kim <jinsukkim@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Laís Minchillo <laisminchillo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577138}