IANAL, but this part from chrome webstore TOS > You agree that you will not engage in any activity with the Web Store, including the development or publication

IANAL, but this part from chrome webstore TOS > You agree that you will not engage in any activity with the Web Store, including the development or publication of Products ... that knowingly violates a third party’s terms of service, sounds like publishing extensions which enable users to violate the Facebook TOS are not ok.