Revert "Remove references to WebContents from PasswordFormManager."

This reverts commit r249382.

It's unclear what broke the tree and I'm trying this revert in the hopes
of finding the problem.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249408 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249408