Add test to check all current accelerators having keyboard overlay.

chrome/browser/resources/chromeos/keyboard_overlay.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // <include src="keyboard_overlay_data.js">
 
 var BASE_KEYBOARD = {
   top: 0,
   left: 0,
   width: 1237,
@@ skipping 27 matching lines @@
 var LABEL_TO_IDENTIFIER = {
   'search': 'E0 5B',
   'ctrl': '1D',
   'alt': '38',
   'caps lock': '3A',
   'esc': '01',
   'backspace': '0E',
   'disabled': 'DISABLED'
 };
 
+// This mapping is maintained for keyboard_overlay_ui_browsertest.

[Lei Zhang, 2017/04/12 22:40:10]

Rather, "for KeyboardOverlayUIBrowserTest."

[wutao, 2017/04/12 22:53:30]

Done.

 var KEYCODE_TO_LABEL = {
   8: 'backspace',
   9: 'tab',
+  10: 'shift',
   13: 'enter',
   27: 'esc',
   32: 'space',
   33: 'pageup',
   34: 'pagedown',
   35: 'end',
   36: 'home',
   37: 'left',
   38: 'up',
   39: 'right',
@@ skipping 19 matching lines @@
   112: 'back',
   113: 'forward',
   114: 'reload',
   115: 'full screen',
   116: 'switch window',
   117: 'bright down',
   118: 'bright up',
   119: 'mute',
   120: 'vol. down',
   121: 'vol. up',
+  152: 'power',
+  166: 'back',
+  167: 'forward',
+  168: 'reload',
+  173: 'mute',
+  174: 'vol. down',
+  175: 'vol. up',
+  183: 'full screen',
+  182: 'switch window',
   186: ';',
   187: '+',
   188: ',',
   189: '-',
   190: '.',
   191: '/',
   192: '`',
+  216: 'bright down',
+  217: 'bright up',
+  218: 'bright down',
   219: '[',
   220: '\\',
   221: ']',
   222: '\'',
+  232: 'bright up',
 };
 
 /**
  * When the top row keys setting is changed so that they're treated as function
  * keys, their labels should change as well.
  */
 var TOP_ROW_KEY_LABEL_TO_FUNCTION_LABEL = {
   'back' : 'f1',
   'forward' : 'f2',
   'reload' : 'f3',
@@ skipping 826 matching lines @@
 function onWidgetShown() {
   setTimeout(function() {
     // Show and focus the instructions div after a delay so that chrome vox
     // speaks it correctly.
     $('instructions').style.visibility = 'visible';
     $('instructions').focus();
   }, 500);
 }
 
 document.addEventListener('DOMContentLoaded', init);