Begin introducing some of the initial pieces for ChromeVox next commands.

chrome/browser/resources/chromeos/chromevox2/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('cvox2.Background');
 goog.provide('cvox2.global');
 
 /** Classic Chrome accessibility API. */
 cvox2.global.accessibility =
     chrome.accessibilityPrivate || chrome.experimental.accessibility;
 
 /**
  * ChromeVox2 background page.
  */
 cvox2.Background = function() {
+  /**
+   * A list of sites to use with ChromeVox next.
+   * @type {!Array.<string>}
+   */
+  this.whitelist_ = ['http://www.chromevox.com/'];
+
   // Only needed with unmerged ChromeVox classic loaded before.
+  // TODO(dtseng): Refactor all tabs handlers out of
+  //accessibility_api_handler.js.
   cvox2.global.accessibility.setAccessibilityEnabled(false);
 
   // Register listeners for ...
   // Desktop.
   chrome.automation.getDesktop(this.onGotTree.bind(this));
 
   // Tabs.
   chrome.tabs.onUpdated.addListener(this.onTabUpdated.bind(this));
-
-  // Keyboard events (currently Messages from content script).
-  chrome.extension.onConnect.addListener(this.onConnect.bind(this));
 };
 
 cvox2.Background.prototype = {
   /**
-   * ID of the port used to communicate between content script and background
-   * page.
-   * @const {string}
-   */
-  PORT_ID: 'chromevox2',
-
-  /**
-   * Handles chrome.extension.onConnect.
-   * @param {Object} port The port.
-   */
-  onConnect: function(port) {
-    if (port.name != this.PORT_ID)
-      return;
-    port.onMessage.addListener(this.onMessage.bind(this));
-  },
-
-  /**
-   * Dispatches messages to specific handlers.
-   * @param {Object} message The message.
-   */
-  onMessage: function(message) {
-    if (message.keyDown)
-      this.onKeyDown(message);
-  },
-
-  /**
-   * Handles key down messages from the content script.
-   * @param {Object} message The key down message.
-   */
-  onKeyDown: function(message) {
-    // TODO(dtseng): Implement.
-  },
-
-  /**
    * Handles chrome.tabs.onUpdate.
    * @param {number} tabId The tab id.
    * @param {Object.<string, (string|boolean)>} changeInfo Information about
    * the updated tab.
    */
   onTabUpdated: function(tabId, changeInfo) {
-    chrome.automation.getTree(this.onGotTree.bind(this));
+    chrome.tabs.get(tabId, function(tab) {
+      var isWhitelisted = this.whitelist_.some(function(item) {
+        return tab.url.indexOf(item) == 0;
+      });
+
+      if (!tab.active || !isWhitelisted) {
+        chrome.commands.onCommand.removeListener(this.onGotCommand);

[dmazzoni, 2014/09/04 15:55:42]

Unless I'm misunderstanding, I don't think you want to do this when a tab is
updated. I'm pretty sure onTabUpdated can get called on a background tab, like
if a background tab decides to refresh or navigate on its own. I think you
should only do this in onActivated.

Also, if you remove the listener do you also need to enable ChromeVox (via
javascript)?

[David Tseng, 2014/09/04 18:37:43]

Done.

Disabling only occurs if the tab is whitelisted. A tab should be enabled by
default.

+        return;
+      }
+
+      if (!chrome.commands.onCommand.hasListener(this.onGotCommand))
+      chrome.commands.onCommand.addListener(this.onGotCommand.bind(this));
+
+      chrome.tabs.executeScript(
+          tab.id,
+          {'code': 'try { window.disableChromeVox(); } catch(e) { }\n',
+           'allFrames': true});
+
+      chrome.automation.getTree(this.onGotTree.bind(this));
+    }.bind(this));
   },
 
   /**
    * Handles all setup once a new automation tree appears.
    * @param {AutomationTree} tree The new automation tree.
    */
   onGotTree: function(root) {
     // Register all automation event listeners.
     root.addEventListener(chrome.automation.EventType.focus,
                           this.onAutomationEvent.bind(this),
                           true);
   },
 
   /**
    * A generic handler for all desktop automation events.
    * @param {AutomationEvent} evt The event.
    */
   onAutomationEvent: function(evt) {
     var output = evt.target.attributes.name + ' ' + evt.target.role;
-    cvox.ChromeVox.tts.speak(output);
+    cvox.ChromeVox.tts.speak(output, 0);

[dmazzoni, 2014/09/04 15:55:42]

please use QUEUE_MODE_FLUSH instead of 0

[David Tseng, 2014/09/04 18:37:43]

Done.

     cvox.ChromeVox.braille.write(cvox.NavBraille.fromText(output));
+  },
+
+  onGotCommand: function(command) {
   }
 };
 
 /** @type {cvox2.Background} */
 cvox2.global.backgroundObj = new cvox2.Background();