Support passing escape item to TouchBar constructor

docs/api/touch-bar.md

@@ -4,9 +4,11 @@
 
 Process: [Main](../tutorial/quick-start.md#main-process)
 
-### `new TouchBar(items)` _Experimental_
+### `new TouchBar(options)` _Experimental_
 
-* `items` ([TouchBarButton](touch-bar-button.md) | [TouchBarColorPicker](touch-bar-color-picker.md) | [TouchBarGroup](touch-bar-group.md) | [TouchBarLabel](touch-bar-label.md) | [TouchBarPopover](touch-bar-popover.md) | [TouchBarScrubber](touch-bar-scrubber.md) | [TouchBarSegmentedControl](touch-bar-segmented-control.md) | [TouchBarSlider](touch-bar-slider.md) | [TouchBarSpacer](touch-bar-spacer.md))[]
+* `options` - Object
+  * `items` ([TouchBarButton](touch-bar-button.md) | [TouchBarColorPicker](touch-bar-color-picker.md) | [TouchBarGroup](touch-bar-group.md) | [TouchBarLabel](touch-bar-label.md) | [TouchBarPopover](touch-bar-popover.md) | [TouchBarScrubber](touch-bar-scrubber.md) | [TouchBarSegmentedControl](touch-bar-segmented-control.md) | [TouchBarSlider](touch-bar-slider.md) | [TouchBarSpacer](touch-bar-spacer.md))[]
+  * `escapeItem` ([TouchBarButton](touch-bar-button.md) | [TouchBarColorPicker](touch-bar-color-picker.md) | [TouchBarGroup](touch-bar-group.md) | [TouchBarLabel](touch-bar-label.md) | [TouchBarPopover](touch-bar-popover.md) | [TouchBarScrubber](touch-bar-scrubber.md) | [TouchBarSegmentedControl](touch-bar-segmented-control.md) | [TouchBarSlider](touch-bar-slider.md) | [TouchBarSpacer](touch-bar-spacer.md)) (optional)
 
 Creates a new touch bar with the specified items. Use
 `BrowserWindow.setTouchBar` to add the `TouchBar` to a window.

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)
     }

spec/api-touch-bar-spec.js

@@ -6,23 +6,28 @@ const {TouchBarButton, TouchBarColorPicker, TouchBarGroup} = TouchBar
 const {TouchBarLabel, TouchBarPopover, TouchBarScrubber, TouchBarSegmentedControl, TouchBarSlider, TouchBarSpacer} = TouchBar
 
 describe('TouchBar module', function () {
-  it('throws an error when created without an items array', function () {
+  it('throws an error when created without an options object', function () {
     assert.throws(() => {
       const touchBar = new TouchBar()
       touchBar.toString()
-    }, /Must specify items array as first argument/)
+    }, /Must specify options object as first argument/)
   })
 
   it('throws an error when created with invalid items', function () {
     assert.throws(() => {
-      const touchBar = new TouchBar([1, true, {}, []])
+      const touchBar = new TouchBar({items: [1, true, {}, []]})
       touchBar.toString()
     }, /Each item must be an instance of TouchBarItem/)
   })
 
   it('throws an error when an invalid escape item is set', function () {
     assert.throws(() => {
-      const touchBar = new TouchBar([])
+      const touchBar = new TouchBar({items: [], escapeItem: 'esc'})
+      touchBar.toString()
+    }, /Escape item must be an instance of TouchBarItem/)
+
+    assert.throws(() => {
+      const touchBar = new TouchBar({items: []})
       touchBar.escapeItem = 'esc'
     }, /Escape item must be an instance of TouchBarItem/)
   })