Add a page to explain earcons in the tutorial

chrome/browser/resources/chromeos/chromevox/strings/chromevox_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 
 <grit base_dir="." current_release="1" latest_public_release="0"
       output_all_resource_defines="false" enc_check="möl" source_lang_id="en">
   <outputs>
     <output filename="_locales/am/messages.json" type="chrome_messages_json" lang="am"/>
     <output filename="_locales/ar/messages.json" type="chrome_messages_json" lang="ar"/>
     <output filename="_locales/bg/messages.json" type="chrome_messages_json" lang="bg"/>
     <output filename="_locales/bn/messages.json" type="chrome_messages_json" lang="bn"/>
     <output filename="_locales/ca/messages.json" type="chrome_messages_json" lang="ca"/>
@@ skipping 2609 matching lines @@
       </message>
       <message desc="Brailled for a UI element that is busy" name="IDS_CHROMEVOX_BUSY_STATE_BRL">
         busy
       </message>
       <message desc="Describes a UI element invoked after pressing enter such as an ok button in a dialog" name="IDS_CHROMEVOX_DEFAULT_STATE">
         default
       </message>
       <message desc="Brailles for a UI element invoked after pressing enter such as an ok button in a dialog" name="IDS_CHROMEVOX_DEFAULT_STATE_BRL">
         default
       </message>
+      <message desc="Title of the earcon page in the ChromeVox tutorial" name="IDS_CHROMEVOX_TUTORIAL_EARCON_PAGE_TITLE">
+        Sounds
+      </message>
+      <message desc="Body text of the earcon page in the ChromeVox tutorial" name="IDS_CHROMEVOX_TUTORIAL_EARCON_PAGE_BODY">
+        ChromeVox uses sounds to give you essential and additional information. You can use these sounds to navigate more quickly by learning what each sound means. Once you get more comfortable, you can turn off verbose descriptions in speech and rely on them for essential information about the page. Here's a complete list of sounds and what they mean.
+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_alert_modal_earcon_description">

[dmazzoni, 2016/11/12 00:03:59]

The name should be all caps, fix throughout

[David Tseng, 2016/11/13 07:32:56]

Done.

+        A modal alert
+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_alert_nonmodal_earcon_description">
+        A non modal alert
+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_button_earcon_description">
+        A button
+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_check_off_earcon_description">
+        An unchecked checkbox
+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_check_on_earcon_description">
+        A checked checkbox
+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_editable_text_earcon_description">
+        An editable text field
+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_invalid_keypress_earcon_description">
+        An invalid key press

[dmazzoni, 2016/11/12 00:03:59]

Note that we use the same sound for invalid key press, and wrap.

Perhaps we should either make them distinct, like changing the pitch of one
would be easy, or change the descriptions

[David Tseng, 2016/11/13 07:32:56]

Filed https://bugs.chromium.org/p/chromium/issues/detail?id=664779 and assigned
to you.

This earcon isn't currently used, so it doesn't really matter I guess. It is
helpful though so perhaps in phase4 we'll add it for unrecognized commands;
let's go with changing the sound.

+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_link_earcon_description">
+        A link
+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_listbox_earcon_description">
+        A listbox or combo box
+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_page_start_loading_earcon_description">
+        A page load in progress
+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_pop_up_button_earcon_description">
+        A pop up button
+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_slider_earcon_description">
+        A slider
+      </message>
+      <message desc="Describes an audio clip that gets played for a specific event or control type. Use the default string as a guide to what the audio clip represents or conveys." name="IDS_CHROMEVOX_wrap_earcon_description">
+        Movement from beginning to end or end to beginning inside of a page, dialog, or other container

[dmazzoni, 2016/11/12 00:03:59]

I think it's fine to use the word "wrap", as in "Wrapping from beginning to end"
or so on

[David Tseng, 2016/11/13 07:32:56]

No strong opinion here, so done.

+      </message>
     </messages>
   </release>
 </grit>