Mojo C++ bindings: add a new mode to generator to use native STL/WTF types

mojo/public/tools/bindings/mojom.gni

 # Copyright 2014 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.
 
 mojom_generator_root = "//mojo/public/tools/bindings"
 mojom_generator_script = "$mojom_generator_root/mojom_bindings_generator.py"
 mojom_generator_sources = [
   "$mojom_generator_root/generators/mojom_cpp_generator.py",
   "$mojom_generator_root/generators/mojom_js_generator.py",
   "$mojom_generator_root/generators/mojom_java_generator.py",
@@ skipping 51 matching lines @@
 #
 #   public_deps (optional)
 #       Note: this can contain only other mojom targets.
 #
 #   import_dirs (optional)
 #       List of import directories that will get added when processing sources.
 #
 #   testonly (optional)
 #
 #   visibility (optional)
+#
+#   use_new_wrapper_types (optional)
+#       If set to true, mojom array/map/string will be mapped to STL (for
+#       chromium variant) or WTF (for blink) types. Otherwise, they will be
+#       mapped to mojo::Array/Map/String/etc.
+#       Default value is false.
+#       TODO(yzshen):
+#         - flip the flag and make use_new_wrapper_types=true the default;
+#         - convert all users to use the new mode;
+#         - remove support for the old mode.
 template("mojom") {
   assert(
       defined(invoker.sources) || defined(invoker.deps) ||
           defined(invoker.public_deps),
       "\"sources\" or \"deps\" must be defined for the $target_name template.")
 
   all_deps = []
   if (defined(invoker.deps)) {
     all_deps += invoker.deps
   }
@@ skipping 130 matching lines @@
 
         args += [
           "--typemap",
           rebase_path(type_mappings_path, root_build_dir),
         ]
 
         if (defined(bindings_configuration.for_blink) &&
             bindings_configuration.for_blink) {
           args += [ "--for_blink" ]
         }
+
+        if (defined(invoker.use_new_wrapper_types) &&
+            invoker.use_new_wrapper_types) {
+          args += [ "--use_new_wrapper_types" ]
+        }
       }
     }
 
     action(type_mappings_target_name) {
       inputs = _bindings_configuration_files
       outputs = [
         type_mappings_path,
       ]
       script = "$mojom_generator_root/generate_type_mappings.py"
       deps = []
@@ skipping 169 matching lines @@
           full_name = get_label_info(d, "label_no_toolchain")
           deps += [ "${full_name}_java" ]
         }
 
         srcjar_deps = [ ":$java_srcjar_target_name" ]
         run_findbugs_override = false
       }
     }
   }
 }