GTK: Hide the "Other Bookmarks" button when there are no bookmarks there.

chrome/browser/ui/gtk/bookmarks/bookmark_bar_gtk.h

Index: chrome/browser/ui/gtk/bookmarks/bookmark_bar_gtk.h
diff --git a/chrome/browser/ui/gtk/bookmarks/bookmark_bar_gtk.h b/chrome/browser/ui/gtk/bookmarks/bookmark_bar_gtk.h
index 208a8ed553ef093719c26e6ce663fe5781a4baa7..8ae89bde2a978ea31c188741a92ba1f12b966238 100644
--- a/chrome/browser/ui/gtk/bookmarks/bookmark_bar_gtk.h
+++ b/chrome/browser/ui/gtk/bookmarks/bookmark_bar_gtk.h
@@ -130,6 +130,10 @@ class BookmarkBarGtk : public ui::AnimationDelegate,
   // Sets the visibility of the overflow chevron.
   void SetChevronState();
 
+  // Shows or hides the other bookmarks button depending on whether there are
+  // bookmarks in it.
+  void UpdateOtherBookmarksVisibility();
+
   // Helper function which destroys all the bookmark buttons in the GtkToolbar.
   void RemoveAllBookmarkButtons();
 
@@ -341,6 +345,10 @@ class BookmarkBarGtk : public ui::AnimationDelegate,
   // bar.
   GtkWidget* overflow_button_;
 
+  // A separator between the main bookmark bar area and
+  // |other_bookmarks_button_|.
+  GtkWidget* other_bookmarks_separator_;
+
   // The other bookmarks button.
   GtkWidget* other_bookmarks_button_;