Add a page to explain earcons in the tutorial

chrome/browser/resources/chromeos/chromevox/host/interface/abstract_earcons.js

Index: chrome/browser/resources/chromeos/chromevox/host/interface/abstract_earcons.js
diff --git a/chrome/browser/resources/chromeos/chromevox/host/interface/abstract_earcons.js b/chrome/browser/resources/chromeos/chromevox/host/interface/abstract_earcons.js
index b33c8cef4351eba788d20bb94bfec84e4a973ed9..7ed1ef5fa8d6372eeed23a402df1f73f35cdeaa1 100644
--- a/chrome/browser/resources/chromeos/chromevox/host/interface/abstract_earcons.js
+++ b/chrome/browser/resources/chromeos/chromevox/host/interface/abstract_earcons.js
@@ -11,6 +11,7 @@
 
 goog.provide('cvox.AbstractEarcons');
 goog.provide('cvox.Earcon');
+goog.provide('cvox.EarconDescription');
 
 
 /**
@@ -47,6 +48,28 @@ cvox.Earcon = {
   WRAP_EDGE: 'wrap_edge',
 };
 
+/**
+ * Maps a earcon id to a message id description.
+ * Only add mappings for earcons used in ChromeVox Next. This map gets
+ * used to generate tutorial content.
+ * @type {Object<string, string>}
+ */
+cvox.EarconDescription = {
+  alert_modal: 'alert_modal_earcon_description',
+  alert_nonmodal: 'alert_nonmodal_earcon_description',
+  button: 'button_earcon_description',
+  check_off: 'check_off_earcon_description',
+  check_on: 'check_on_earcon_description',
+  editable_text: 'editable_text_earcon_description',
+  invalid_keypress: 'invalid_keypress_earcon_description',
+  link: 'link_earcon_description',
+  listbox: 'listbox_earcon_description',
+  page_start_loading: 'page_start_loading_earcon_description',
+  pop_up_button: 'pop_up_button_earcon_description',
+  slider: 'slider_earcon_description',
+  wrap: 'wrap_earcon_description',
+};
+
 
 /**
  * @constructor