Select or deselect all checklist items present on a page (for example history items on chrome://history-frame). When invoking checkAll, the argument checkVal should be set to "true" to check all, and "false" to deselect (uncheck).

Checklist bulk manipulator

function checkAll(checkVal){
  var removeMult = document.getElementById("remove-selected");
  removeMult.removeAttribute("disabled");
  var c = [];
  c = document.getElementsByTagName('input');
  console.log(c);
  for (var i = 0; i < c.length; i++)
  {
    if (c[i].type == 'checkbox')
    {
      c[i].checked = checkVal;
    }
  }
};
// pass "true" in order to check all
checkAll(true);

When on chrome://history-frame also add the below to enable the "Remove selected items" button:
var removeMult = document.getElementById("remove-selected");
removeMult.removeAttribute("disabled");