[Autofill] Fix up AutofillAgent a bit.

* Remove an obsolete code path (Blink side is in a separate patch).
* Re-wrap some IPC handler lines to 80-col

BUG=330077
TEST=none
R=estade@chromium.org

Review URL: https://codereview.chromium.org/119683003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242054 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242054