code: function addPopUp($popUp, removeHandler, autoRemove) {
          autoRemove = autoRemove || false;
  
          _popUps.push($popUp[0]);
          $popUp.data("PopUpManager-autoRemove", autoRemove);
          $popUp.data("PopUpManager-removeHandler", removeHandler);
      }
docs: Add Esc key handling for a popup DOM element.
  
  @param {!jQuery} $popUp jQuery object for the DOM element pop-up
  @param {function} removeHandler Pop-up specific remove (e.g. display:none or DOM removal)
  @param {?Boolean} autoRemove - Specify true to indicate the PopUpManager should
  remove the popup from the _popUps array when the popup is closed. Specify false
  when the popup is always persistant in the _popUps array.