Support passing escape item to TouchBar constructor

lib/browser/api/touch-bar.js

@@ -20,17 +20,29 @@ class TouchBar extends EventEmitter {
     touchBar._addToWindow(window)
   }
 
-  constructor (items) {
+  constructor (options) {
     super()
 
+    if (options == null) {
+      throw new Error('Must specify options object as first argument')
+    }
+
+    let {items, escapeItem} = options
+
+    // FIXME Support array as first argument, remove in 2.0
+    if (Array.isArray(options)) {
+      items = options
+      escapeItem = null
+    }
+
     if (!Array.isArray(items)) {
-      throw new Error('Must specify items array as first argument')
+      items = []
     }
 
     this.windowListeners = {}
     this.items = {}
     this.ordereredItems = []
-    this.escapeItem = null
+    this.escapeItem = escapeItem
     this.changeListener = (item) => {
       this.emit('change', item.id, item.type)
     }