Adjust ChromeVox (spoken feedback) strings and make it possible for announcemen

chrome/common/extensions/api/experimental_accessibility.json

 // Copyright (c) 2012 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.
 
 [
   {
     "namespace": "experimental.accessibility",
     "compiler_options": {
       "implemented_in": "chrome/browser/accessibility/accessibility_extension_api.h"
     },
@@ skipping 275 matching lines @@
         "name": "onMenuClosed",
         "type": "function",
         "description": "Fired when a menu is closed.",
         "parameters": [
           {
             "$ref": "AccessibilityObject",
             "name": "menu",
             "description": "Information about the menu that was closed."
           }
         ]
+      },
+      {
+        "name": "onSpokenFeedbackEnabled",
+        "type": "function",
+        "description": "Fired when spoken feedback is enabled.",
+        "parameters": [
+          {
+            "type": "function",
+            "name": "callback",
+            "optional": true,
+            "parameters": [
+              {
+                "type": "boolean",
+                "name": "makeAnnouncements",
+                "description": "Whether to make introductory announcements."
+              }
+            ]
+          }
+        ]
+      },
+      {
+        "name": "onSpokenFeedbackDisabled",
+        "type": "function",
+        "description": "Fired when spoken feedback is disabled."
       }
     ]
   }
 ]