GitLab

This CL enables autosizing for extension options guests using
the built-in autosizing functionality in GuestViewBase.

BUG=386838

Review URL: https://codereview.chromium.org/431503002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@287993 0039d316-1c4b-4281-b951-d872f2087c98