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

mojo/mojom_bindings_generator_explicit.gypi

 # Copyright 2013 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.
 
 {
   'includes': [
     'mojom_bindings_generator_variables.gypi',
   ],
   'variables': {
     'variables': {
       'variables': {
         'for_blink%': 'false',
-        'use_new_wrapper_types%': 'false',
+        'use_new_wrapper_types%': 'true',
       },
       'for_blink%': 'false',
-      'use_new_wrapper_types%': 'false',
+      'use_new_wrapper_types%': 'true',
       'conditions': [
         ['for_blink=="true"', {
           'mojom_output_languages%': 'c++',
           'mojom_variant%': 'blink',
           'mojom_generator_wtf_arg%': [
             '--for_blink',
           ],
           'wtf_dependencies%': [
             '<(DEPTH)/mojo/mojo_public.gyp:mojo_cpp_bindings_wtf_support',
             '<(DEPTH)/third_party/WebKit/Source/wtf/wtf.gyp:wtf',
@@ skipping 159 matching lines @@
         ],
         'additional_input_paths': [
           '<@(mojom_bindings_generator_sources)',
           '<@(mojom_files)',
         ],
         'mojom_generated_sources': [ '<@(mojom_generated_outputs)' ],
       },
     }
   },
 }