Moving Background App support on the Mac Dock menu into its own submenu

chrome/app/generated_resources.grd

 <?xml version="1.0" encoding="UTF-8"?>
 
 <!-- This file contains definitions of resources that will be translated for
 each locale. -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       source_lang_id="en" enc_check="möl">
   <outputs>
     <output filename="grit/generated_resources.h" type="rc_header">
       <emit emit_type='prepend'></emit>
@@ skipping 9112 matching lines @@
         <!-- File menu -->
         <message name="IDS_NEW_TAB_MAC" desc="The Mac menu item for opening a new tab in the file menu.">
           New Tab
         </message>
         <message name="IDS_NEW_WINDOW_MAC" desc="The Mac menu item for opening a new window in the file menu.">
           New Window
         </message>
         <message name="IDS_NEW_INCOGNITO_WINDOW_MAC" desc="The Mac menu item for opening a new incognito window in the file menu.">
           New Incognito Window
         </message>
+        <message name="IDS_BACKGROUND_APPS_MAC" desc="The Mac submenu for opening Background Apps.">
+          Background Apps
+        </message>
         <message name="IDS_REOPEN_CLOSED_TABS_MAC" desc="The Mac menu item reopen recently closed tabs in the file menu.">
           Reopen Closed Tab
         </message>
         <message name="IDS_OPEN_FILE_MAC" desc="The Mac menu item to open a file in the file menu.">
           Open File...
         </message>
         <message name="IDS_OPEN_LOCATION_MAC" desc="The Mac menu item to open a location in the file menu (puts cursor in the url bar).">
           Open Location...
         </message>
         <message name="IDS_CREATE_APPLICATION_MAC" desc="The Mac menu item to create an application shortcut in the file menu.">
@@ skipping 2601 matching lines @@
     </includes>
     <structures fallback_to_english="true">
       <structure name="IDD_CHROME_FRAME_FIND_DIALOG" file="cf_resources.rc" type="dialog" >
       </structure>
       <structure name="IDD_CHROME_FRAME_READY_PROMPT" file="cf_resources.rc" type="dialog" >
       </structure>
     </structures>
 
   </release>
 </grit>