Make ChromeVox Next swallow key events that correspond to commands.

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

 // Copyright 2014 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 The entry point for all ChromeVox2 related code for the
  * background page.
  */
 
 goog.provide('Background');
@@ skipping 101 matching lines @@
     get: function() {
       return localStorage['active'] !== 'false';
     },
     set: function(value) {
       localStorage['active'] = value;
     }
   });
 
   cvox.ExtensionBridge.addMessageListener(this.onMessage_);
 
-  document.addEventListener(
-      'keydown', cvox.ChromeVoxKbHandler.basicKeyDownActionsListener, true);
+  document.addEventListener('keydown', this.onKeyDown.bind(this), true);
   cvox.ChromeVoxKbHandler.commandHandler = this.onGotCommand.bind(this);
 
   // Classic keymap.
   cvox.ChromeVoxKbHandler.handlerKeyMap = cvox.KeyMap.fromDefaults();
 
   chrome.automation.addTreeChangeObserver(this.onTreeChange);
 };
 
 Background.prototype = {
   /** Forces ChromeVox Next to be active for all tabs. */
@@ skipping 272 matching lines @@
 
       new Output().withSpeechAndBraille(
               this.currentRange_, prevRange, Output.EventType.NAVIGATE)
           .go();
     }
 
     return false;
   },
 
   /**
+   * 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) {
+    if (!cvox.ChromeVoxKbHandler.basicKeyDownActionsListener(evt)) {

[David Tseng, 2015/11/19 01:11:50]

Sorry missed something here. This needs to be mode aware: classic should never
eat keys and not attempt to process the command at all.

+      evt.preventDefault();
+      evt.stopPropagation();
+    }
+  },
+
+  /**
    * Open the options page in a new tab.
    */
   showOptionsPage: function() {
     var optionsPage = {url: 'chromevox/background/options.html'};
     chrome.tabs.create(optionsPage);
   },
 
   /**
    * Handles a braille command.
    * @param {!cvox.BrailleKeyEvent} evt
@@ skipping 245 matching lines @@
     return glob.replace(/[.+^$(){}|[\]\\]/g, '\\$&')
         .replace(/\*/g, '.*')
         .replace(/\?/g, '.');
   }).join('|') + ')$');
 };
 
 /** @type {Background} */
 global.backgroundObj = new Background();
 
 });  // goog.scope