Ensure spoken feedback keyboard hooks prevent re-injection of key up events

chrome/browser/resources/chromeos/chromevox/cvox2/background/keyboard_handler.js

 // Copyright 2016 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.
 
 /**
  * @fileoverview ChromeVox keyboard handler.
  */
 
 goog.provide('BackgroundKeyboardHandler');
 
 goog.require('cvox.ChromeVoxKbHandler');
 
 /** @constructor */
 BackgroundKeyboardHandler = function() {
   // Classic keymap.
   cvox.ChromeVoxKbHandler.handlerKeyMap = cvox.KeyMap.fromDefaults();
 
   /** @type {number} @private */
   this.passThroughKeyUpCount_ = 0;
 
+  /** @type {Array<number>} @private */
+  this.preventedKeys_ = [];
+
   document.addEventListener('keydown', this.onKeyDown.bind(this), false);
   document.addEventListener('keyup', this.onKeyUp.bind(this), false);
 };
 
 BackgroundKeyboardHandler.prototype = {
   /**
    * Handles key down events.
    * @param {Event} evt The key down event to process.
    * @return {boolean} True if the default action should be performed.
    */
   onKeyDown: function(evt) {
     evt.stickyMode = cvox.ChromeVox.isStickyModeOn() && cvox.ChromeVox.isActive;
     if (cvox.ChromeVox.passThroughMode)
       return false;
 
     if (ChromeVoxState.instance.mode != ChromeVoxMode.CLASSIC &&
         ChromeVoxState.instance.mode != ChromeVoxMode.NEXT_COMPAT &&
         !cvox.ChromeVoxKbHandler.basicKeyDownActionsListener(evt)) {
       evt.preventDefault();
       evt.stopPropagation();
+      this.preventedKeys_.push(evt.keyCode);
     }
     Output.forceModeForNextSpeechUtterance(cvox.QueueMode.FLUSH);
     return false;
   },
 
   /**
    * Handles key up events.
    * @param {Event} evt The key down event to process.
    * @return {boolean} True if the default action should be performed.
    */
   onKeyUp: function(evt) {
     // Reset pass through mode once a keyup (not involving the pass through key)
     // is seen. The pass through command involves three keys.
     if (cvox.ChromeVox.passThroughMode) {
       if (this.passThroughKeyUpCount_ >= 3) {
         cvox.ChromeVox.passThroughMode = false;
         this.passThroughKeyUpCount_ = 0;
       } else {
         this.passThroughKeyUpCount_++;
       }
     }
+
+    var wasDown = false;
+    var updatedKeys = [];
+    for (var i = 0; i < this.preventedKeys_.length; i++) {

[dmazzoni, 2016/12/06 07:25:22]

If you make preventedKeys_ a Set(), I think you can replace all of this code
with just this:

if (this.preventedKeys_.has(evt.keyCode)) {
  this.preventedKeys_.delete(evt.keyCode);
  evt.preventDefault();
  evt.stopPropagation();
}

[David Tseng, 2016/12/06 16:55:53]

Sure. Was storing the entire event before. Changed to use a set.

+      var otherKeyCode = this.preventedKeys_[i];
+      if (otherKeyCode == evt.keyCode)
+        wasDown = true;
+      else
+        updatedKeys.push(otherKeyCode);
+    }
+    this.preventedKeys_ = updatedKeys;
+
+    if (wasDown) {
+      evt.preventDefault();
+      evt.stopPropagation();
+    }
     return false;
   },
 
   /**
    * React to mode changes.
    * @param {ChromeVoxMode} newMode
    * @param {ChromeVoxMode?} oldMode
    */
   onModeChanged: function(newMode, oldMode) {
     if (newMode == ChromeVoxMode.CLASSIC ||
@@ skipping 12 matching lines @@
       window['prefs'].switchToKeyMap('keymap_next');
     } else if (oldMode &&
         oldMode != ChromeVoxMode.CLASSIC &&
         oldMode != ChromeVoxMode.CLASSIC_COMPAT) {
       // Switching out of next. Intentionally do nothing when switching out of
       // an uninitialized |oldMode|.
       window['prefs'].switchToKeyMap('keymap_classic');
     }
   }
 };