Making bookmark folder context menu display the number of bookmarks that will be opened by Open All

chrome/app/bookmarks_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Bookmarks specific strings (included from generated_resources.grd). -->
 <grit-part>
   <!-- Begin of Bookmarks Bar strings-->
   <if expr="not is_android">
     <!-- The following two strings are shown when the user has no bookmarks yet. -->
     <message name="IDS_BOOKMARKS_NO_ITEMS" desc="Text shown when the user has no bookmarks">
       For quick access, place your bookmarks here on the bookmarks bar.
     </message>
     <message name="IDS_BOOKMARK_BAR_IMPORT_LINK" desc="text shown for importing ">
@@ skipping 45 matching lines @@
   <message name="IDS_BOOKMARK_BAR_APPS_SHORTCUT_NAME" desc="Name shown in the bookmark bar for the apps page shortcut">
     Apps
   </message>
   <message name="IDS_BOOKMARK_BAR_APPS_SHORTCUT_TOOLTIP" desc="Text shown in the tooltip of the apps page shortcut in the bookmark bar">
     Show apps
   </message>
   <!-- End of Bookmarks Bar strings. -->
 
   <!-- Begin of Bookmarks Bar Context Menu strings. -->
   <if expr="not use_titlecase">
-    <message name="IDS_BOOKMARK_BAR_OPEN_ALL" desc="Menu title for opening all urls in a bookmark folder">
-      &amp;Open all bookmarks
-    </message>
-    <message name="IDS_BOOKMARK_BAR_OPEN_ALL_NEW_WINDOW" desc="Menu title for opening all urls in a bookmark folder in a new window">
-      Open all bookmarks in &amp;new window
-    </message>
-    <message name="IDS_BOOKMARK_BAR_OPEN_ALL_INCOGNITO" desc="Menu description for opening all urls in a bookmark folder in an incognito window">
-      Open all bookmarks in &amp;incognito window
-    </message>
+  <message name="IDS_BOOKMARK_BAR_OPEN_ALL" desc="Menu title for opening all urls in a bookmark folder">
+      {COUNT, plural,
+        =0 {&amp;Open all}
+        =1 {&amp;Open bookmark}
+        other {&amp;Open all (#)}}
+  </message>
+  <message name="IDS_BOOKMARK_BAR_OPEN_ALL_NEW_WINDOW" desc="Menu title for opening all urls in a bookmark folder in a new window">
+      {COUNT, plural,
+        =0 {Open all in &amp;new window}
+        =1 {Open in &amp;new window}
+        other {Open all (#) in &amp;new window}}
+  </message>
+  <message name="IDS_BOOKMARK_BAR_OPEN_ALL_INCOGNITO" desc="Menu description for opening all urls in a bookmark folder in an incognito window">
+      {COUNT, plural,
+        =0 {Open all in &amp;incognito window}
+        =1 {Open in &amp;incognito window}
+        other {Open all (#) in &amp;incognito window}}
+  </message>
     <message name="IDS_BOOKMARK_BAR_OPEN_IN_NEW_TAB" desc="Menu description for loading bookmark in a new tab">
       &amp;Open in new tab
     </message>
     <message name="IDS_BOOKMARK_BAR_OPEN_IN_NEW_WINDOW" desc="Menu description for loading bookmark in a new window">
       Open in &amp;new window
     </message>
     <message name="IDS_BOOKMARK_BAR_OPEN_INCOGNITO" desc="Menu description for opening bookmark in incognito window">
       Open in &amp;incognito window
     </message>
     <message name="IDS_BOOKMARK_BAR_EDIT" desc="Title of the bookmark context menu item that brings up the bookmark editor">
@@ skipping 11 matching lines @@
     <message name="IDS_BOOKMARK_BAR_NEW_FOLDER" desc="Menu title for adding a new folder">
       Add &amp;folder...
     </message>
     <if expr="not is_android">
       <message name="IDS_SHOW_BOOKMARK_BAR" desc="The toggle to show the bookmark bar">
         &amp;Show bookmarks bar
       </message>
     </if>
   </if>
   <if expr="use_titlecase">
-    <message name="IDS_BOOKMARK_BAR_OPEN_ALL" desc="In Title Case: Menu title for opening all urls in a bookmark folder">
-      &amp;Open All Bookmarks
-    </message>
-    <message name="IDS_BOOKMARK_BAR_OPEN_ALL_NEW_WINDOW" desc="In Title Case: Menu title for opening all urls in a bookmark folder in a new window">
-      Open All Bookmarks in &amp;New Window
-    </message>
-    <message name="IDS_BOOKMARK_BAR_OPEN_ALL_INCOGNITO" desc="In Title Case: Menu description for opening all urls in a bookmark folder in an incognito window">
-      Open All Bookmarks in &amp;Incognito Window
-    </message>
+  <message name="IDS_BOOKMARK_BAR_OPEN_ALL" desc="In Title Case: Menu title for opening all urls in a bookmark folder">
+      {COUNT, plural,
+        =0 {&amp;Open All}
+        =1 {&amp;Open Bookmark}
+        other {&amp;Open All (#)}}
+  </message>
+  <message name="IDS_BOOKMARK_BAR_OPEN_ALL_NEW_WINDOW" desc="In Title Case: Menu title for opening all urls in a bookmark folder in a new window">
+      {COUNT, plural,
+        =0 {Open All in &amp;New Window}
+        =1 {Open in &amp;New Window}
+        other {Open All (#) in &amp;New Window}}
+  </message>
+  <message name="IDS_BOOKMARK_BAR_OPEN_ALL_INCOGNITO" desc="In Title Case: Menu description for opening all urls in a bookmark folder in an incognito window">
+      {COUNT, plural,
+        =0 {Open All in &amp;Incognito Window}
+        =1 {Open in &amp;Incognito Window}
+        other {Open All (#) in &amp;Incognito Window}}
+  </message>
     <message name="IDS_BOOKMARK_BAR_OPEN_IN_NEW_TAB" desc="In Title Case: Menu description for loading bookmark in a new tab">
       &amp;Open in New Tab
     </message>
     <message name="IDS_BOOKMARK_BAR_OPEN_IN_NEW_WINDOW" desc="In Title Case: Menu description for loading bookmark in a new window">
       Open in &amp;New Window
     </message>
     <message name="IDS_BOOKMARK_BAR_OPEN_INCOGNITO" desc="In Title Case: Menu description for opening bookmark in incognito window">
       Open in &amp;Incognito Window
     </message>
     <message name="IDS_BOOKMARK_BAR_EDIT" desc="In Title Case: Title of the bookmark context menu item that brings up the bookmark editor">
@@ skipping 280 matching lines @@
   </if>
   <!-- End of Bookmarks Menu (in the Main Menu) strings. -->
 
   <!-- Begin of Bookmark Star button strings. -->
   <message name="IDS_TOOLTIP_STARRED" desc="The tooltip shown when you hover the star button in the right side of the location bar and the current page is bookmarked.">
     Edit bookmark for this page
   </message>
   <!-- End of Bookmark Star button strings. -->
 
 </grit-part>