Revert r155743, "Switch Extensions::TabHelper to use WebContents, WebContentsUserData."

BUG=107201
TEST=no visible change
[email protected], [email protected]

Review URL: https://chromiumcodereview.appspot.com/10914186

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@155901 0039d316-1c4b-4281-b951-d872f2087c98
45 files changed