Fix WeakPtrFactory member order in net/socket/.

This CL also adds some missing DISALLOW_COPY_AND_ASSIGN macros in the affected files.

BUG=303818

Review URL: https://codereview.chromium.org/62973003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234182 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234182