Mojo C++ bindings: make the generator use STL/WTF string/vector/map by default.

ui/gfx/geometry/mojo/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//mojo/public/tools/bindings/mojom.gni")
 
 # This target does NOT depend on skia. One can depend on this target to avoid
 # picking up a dependency on skia.
 mojom("mojo") {
   sources = [
     "geometry.mojom",
   ]
+
+  use_new_wrapper_types = false
 }
 
 mojom("test_interfaces") {
   sources = [
     "geometry_traits_test_service.mojom",
   ]
 
   public_deps = [
     ":mojo",
   ]
+
+  use_new_wrapper_types = false
 }
 
 source_set("unit_test") {
   testonly = true
 
   sources = [
     "geometry_struct_traits_unittest.cc",
   ]
 
   deps = [
     ":test_interfaces",
     "//base",
     "//mojo/public/cpp/bindings",
     "//testing/gtest",
     "//ui/gfx/geometry",
   ]
 }