code: function setupContextMenu() {
    var enableContextMenuItem = contextMenu.Item({
      label: 'Enable For This URL',
      data: 'toggle',
      contentScript:
          "self.on('context', function(node) {" +
          "  var hasWtf = !!document.querySelector('.wtf_a');" +
          "  return !hasWtf ? 'Enable For This URL' : 'Disable For This URL';" +
          "});"
    });
    var resetSettingsContextMenuItem = contextMenu.Item({
      label: 'Reset Settings For This URL',
      data: 'reset'
    });
    var showUiContextMenuItem = contextMenu.Item({
      label: 'Show UI',
      data: 'show_ui'
    });
    var rootContextMenuItem = contextMenu.Menu({
      label: 'Tracing Framework',
      items: [
        enableContextMenuItem,
        resetSettingsContextMenuItem,
        contextMenu.Separator(),
        showUiContextMenuItem
      ],
      contentScript:
          "self.on('click', function(node, data) {" +
          "  self.postMessage(data);" +
          "});",
      onMessage: function(action) {
        switch (action) {
          case 'toggle':
            toggleInjectionForActiveTab();
            break;
          case 'reset':
            resetOptionsForActiveTab();
            break;
          case 'show_ui':
            showUi();
            break;
        }
      }
    });
  }
docs: Sets up the page context menu.