Added to options page to let users change keyboard mappings.

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

 // Copyright 2017 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.
 
 /**
  * Alias for document.getElementById.
  *
  * @param  {string} id
  * @return {Element}
  */
 let $ = function(id) {
   // eslint-disable-next-line no-restricted-properties
   return document.getElementById(id);
 };
 
 /**
  * Class to manage the options page.
  *
  * @constructor
  */
 function SwitchAccessOptions() {
   let background = chrome.extension.getBackgroundPage();
 
   /**
-   * User preferences.
+   * SwitchAccess reference.
    *
-   * @type {SwitchAccessPrefs}
+   * @private {SwitchAccessInterface}
    */
-  this.switchAccessPrefs_ = background.switchAccess.switchAccessPrefs;
+  this.switchAccess_ = background.switchAccess;
 
   this.init_();
   document.addEventListener('change', this.handleInputChange_.bind(this));
   background.document.addEventListener(
       'prefsUpdate', this.handlePrefsUpdate_.bind(this));
 }
 
 SwitchAccessOptions.prototype = {
   /**
    * Initialize the options page by setting all elements representing a user
    * preference to show the correct value.
    *
    * @private
    */
   init_: function() {
     $('enableAutoScan').checked =
-        this.switchAccessPrefs_.getBooleanPref('enableAutoScan');
+        this.switchAccess_.getBooleanPref('enableAutoScan');
     $('autoScanTime').value =
-        this.switchAccessPrefs_.getNumberPref('autoScanTime') / 1000;
+        this.switchAccess_.getNumberPref('autoScanTime') / 1000;
+
+    for (let command of this.switchAccess_.getCommands()) {
+      $(command).value =
+          String.fromCharCode(this.switchAccess_.getNumberPref(command));
+    }
   },
 
   /**
    * Handle a change by the user to an element representing a user preference.
    *
    * @param {!Event} event
    * @private
    */
   handleInputChange_: function(event) {
     let input = event.target;
     switch (input.id) {
       case 'enableAutoScan':
-        this.switchAccessPrefs_.setPref(input.id, input.checked);
+        this.switchAccess_.setPref(input.id, input.checked);
         break;
       case 'autoScanTime':
-        let oldVal = this.switchAccessPrefs_.getNumberPref(input.id);
+        let oldVal = this.switchAccess_.getNumberPref(input.id);
         let val = Number(input.value) * 1000;
         let min = Number(input.min) * 1000;
-        if (this.isValidInput_(val, oldVal, min)) {
+        if (this.isValidScanTimeInput_(val, oldVal, min)) {
           input.value = Number(input.value);
-          this.switchAccessPrefs_.setPref(input.id, val);
+          this.switchAccess_.setPref(input.id, val);
         } else {
           input.value = oldVal;
         }
         break;
+      default:
+        if (this.switchAccess_.getCommands().includes(input.id)) {
+          let keyCode = input.value.toUpperCase().charCodeAt(0);
+          if (this.isValidKeyCode_(keyCode)) {
+            input.value = input.value.toUpperCase();
+            this.switchAccess_.setPref(input.id, keyCode);
+          } else {
+            let oldKeyCode = this.switchAccess_.getNumberPref(input.id);
+            input.value = String.fromCharCode(oldKeyCode);
+          }
+        }
     }
   },
 
   /**
+   * Return true if |keyCode| is a letter or number, and if it is not already
+   * being used.
+   *
+   * @param {number} keyCode
+   * @return {boolean}
+   */
+  isValidKeyCode_: function(keyCode) {
+    return ((keyCode >= '0'.charCodeAt(0) && keyCode <= '9'.charCodeAt(0)) ||
+            (keyCode >= 'A'.charCodeAt(0) && keyCode <= 'Z'.charCodeAt(0))) &&
+        !this.switchAccess_.keyCodeIsUsed(keyCode);
+  },
+
+  /**
    * Return true if the input is a valid autoScanTime input. Otherwise, return
    * false.
    *
    * @param {number} value
    * @param {number} oldValue
    * @param {number} min
    * @return {boolean}
    */
-  isValidInput_: function(value, oldValue, min) {
+  isValidScanTimeInput_: function(value, oldValue, min) {
     return (value !== oldValue) && (value >= min);
   },
 
   /**
    * Handle a change in user preferences.
    *
    * @param {!Event} event
    * @private
    */
   handlePrefsUpdate_: function(event) {
     let updatedPrefs = event.detail;
     for (let key of Object.keys(updatedPrefs)) {
       switch (key) {
         case 'enableAutoScan':
           $(key).checked = updatedPrefs[key];
           break;
         case 'autoScanTime':
           $(key).value = updatedPrefs[key] / 1000;
           break;
+        default:
+          if (this.switchAccess_.getCommands().includes(key))
+            $(key).value = String.fromCharCode(updatedPrefs[key]);
       }
     }
   }
 };
 
 document.addEventListener('DOMContentLoaded', function() {
   new SwitchAccessOptions();
 });