[CleanUp] Use base::STLSetDifference in place of std::set_difference

chrome/common/extensions/permissions/permission_set.cc

Index: chrome/common/extensions/permissions/permission_set.cc
diff --git a/chrome/common/extensions/permissions/permission_set.cc b/chrome/common/extensions/permissions/permission_set.cc
index 4fd0bd789946124c2cea5325889d19a1cc8e21c8..ffcc2b2441887873d66d0a618c310526d4f5c7b9 100644
--- a/chrome/common/extensions/permissions/permission_set.cc
+++ b/chrome/common/extensions/permissions/permission_set.cc
@@ -543,11 +543,9 @@ bool PermissionSet::HasLessHostPrivilegesThan(
   // considered an elevation, even though it is not (http://crbug.com/65337).
   std::set<std::string> new_hosts_set(GetDistinctHosts(new_list, false, false));
   std::set<std::string> old_hosts_set(GetDistinctHosts(old_list, false, false));
-  std::set<std::string> new_hosts_only;
-
-  std::set_difference(new_hosts_set.begin(), new_hosts_set.end(),
-                      old_hosts_set.begin(), old_hosts_set.end(),
-                      std::inserter(new_hosts_only, new_hosts_only.begin()));
+  std::set<std::string> new_hosts_only =
+      base::STLSetDifference<std::set<std::string> >(new_hosts_set,
+                                                     old_hosts_set);
 
   return !new_hosts_only.empty();
 }