Set keys for SwitchAccessEventHandler to capture using accessibiltyPrivate API

chrome/browser/resources/chromeos/switch_access/keyboard_handler.js

Index: chrome/browser/resources/chromeos/switch_access/keyboard_handler.js
diff --git a/chrome/browser/resources/chromeos/switch_access/keyboard_handler.js b/chrome/browser/resources/chromeos/switch_access/keyboard_handler.js
index 901690f594341130f35ad6a27d4705825c56683c..c3832851c4cd1592618e8f6a48a35b80a355a4aa 100644
--- a/chrome/browser/resources/chromeos/switch_access/keyboard_handler.js
+++ b/chrome/browser/resources/chromeos/switch_access/keyboard_handler.js
@@ -28,6 +28,11 @@ KeyboardHandler.prototype = {
    * @private
    */
   init_: function() {
+    // Capture keycodes for keys 1 through 4, and 6 through 9.
+    chrome.accessibilityPrivate.setSwitchAccessKeys(
+        ['1'.charCodeAt(0), '2'.charCodeAt(0), '3'.charCodeAt(0),

[Devlin, 2017/05/30 19:22:03]

optional: to me, this would potentially be more readable (and less prone to
error) as:
// Capture keycodes for keys 1 through 4, and 6 through 9.
var keys = ['1', '2', '3', '4', '6', '7', '8', '9'].map(function(key) { return
key.charCodeAt(0); });

But up to you.

[elichtenberg, 2017/05/31 00:58:43]

Good idea. I changed it to an arrow function too, so that should also make it
cleaner.

+        '4'.charCodeAt(0), '6'.charCodeAt(0), '7'.charCodeAt(0),
+        '8'.charCodeAt(0), '9'.charCodeAt(0)]);
     document.addEventListener('keyup', this.handleKeyEvent_.bind(this));
   },