Add a variable use_system_xcode to GN.

chrome/app/nibs/BUILD.gn

Index: chrome/app/nibs/BUILD.gn
diff --git a/chrome/app/nibs/BUILD.gn b/chrome/app/nibs/BUILD.gn
index 0be22170e55f675f8f566acc7ea7a2cd8945e624..67ca3afbc836419fcd189f43844e874e41db54f5 100644
--- a/chrome/app/nibs/BUILD.gn
+++ b/chrome/app/nibs/BUILD.gn
@@ -67,6 +67,15 @@ action("localizer_table") {
   outputs = [
     table_path,
   ]
-  args = [ rebase_path(table_path, root_build_dir) ] +
-         rebase_path(translated_xibs, root_build_dir)
+  args = [
+    "--output_path",
+    rebase_path(table_path, root_build_dir),
+  ]
+  if (!use_system_xcode) {
+    args += [
+      "--developer_dir",
+      hermetic_xcode_path,
+    ]
+  }
+  args += rebase_path(translated_xibs, root_build_dir)
 }