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

components/leveldb/leveldb.gyp

 # 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.
 
 {
   'variables': {
     # This turns on e.g. the filename-based detection of which
     # platforms to include source files on (e.g. files ending in
     # _mac.h or _mac.cc are only compiled on MacOSX).
     'chromium_code': 1,
@@ skipping 50 matching lines @@
         'leveldb_bindings_mojom',
       ],
     },
     {
       'target_name': 'leveldb_bindings_mojom',
       'type': 'none',
       'variables': {
         'mojom_files': [
           'public/interfaces/leveldb.mojom',
         ],
+        'use_new_wrapper_types': 'false',
       },
       'dependencies': [
         '../../components/filesystem/filesystem.gyp:filesystem_bindings_mojom',
       ],
       'includes': [
         '../../mojo/mojom_bindings_generator_explicit.gypi',
       ],
     }
   ],
 }