Mojo C++ bindings: support mapping mojo string to WTF::String.

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 46 matching lines @@
 #   typemap_deps (optional)
 #       A list of public dependencies needed to support active typemaps.
 #
 #   variant (optional)
 #       A variant name to apply to generated bindings. Variant influences
 #       generated source filenames as wells the symbols they define.
 #
 #   testonly (optional)
 #
 #   visibility (optional)
+#
+#   use_wtf_types (optional, C++ only)

[Ken Rockot(use gerrit already), 2016/03/01 02:06:37]

nit: How about more generically something like for_blink? I would like to use
the same flag to generate blink JS bindings eventually

[yzshen1, 2016/03/01 18:42:46]

Sounds good. Done.

+#       Use WTF types as generated type for mojo string/array/map.
 template("mojom") {
   assert(
       defined(invoker.sources) || defined(invoker.deps) ||
           defined(invoker.public_deps),
       "\"sources\" or \"deps\" must be defined for the $target_name template.")
 
   cpp_sources_suffix = "cpp_sources"
   cpp_sources_target_name = "${target_name}_${cpp_sources_suffix}"
   cpp_only = false
   if (defined(invoker.sources)) {
@@ skipping 79 matching lines @@
 
       if (defined(invoker.typemaps)) {
         foreach(typemap, invoker.typemaps) {
           args += [
             "--typemap",
             rebase_path(typemap, root_build_dir),
           ]
         }
         inputs += invoker.typemaps
       }
+
+      if (defined(invoker.use_wtf_types) && invoker.use_wtf_types) {
+        args += [ "--use_wtf_types" ]
+      }
     }
   }
 
   source_set(target_name) {
     if (defined(invoker.visibility)) {
       visibility = invoker.visibility
     }
     if (defined(invoker.testonly)) {
       testonly = invoker.testonly
     }
@@ skipping 70 matching lines @@
       foreach(d, all_deps) {
         # Resolve the name, so that a target //mojo/something becomes
         # //mojo/something:something and we can append cpp_sources_suffix to
         # get the cpp dependency name.
         full_name = get_label_info(d, "label_no_toolchain")
         deps += [ "${full_name}_${cpp_sources_suffix}" ]
       }
       if (!defined(invoker.with_environment) || invoker.with_environment) {
         deps += [ "//mojo/environment:chromium" ]
       }
+      if (defined(invoker.use_wtf_types) && invoker.use_wtf_types) {
+        public_deps += [
+          "//mojo/public/cpp/bindings:wtf_support",
+          "//third_party/WebKit/Source/wtf",
+        ]
+      }
     }
   }
 
   if (is_android && !defined(invoker.variant)) {
     import("//build/config/android/rules.gni")
 
     java_srcjar_target_name = target_name + "_java_sources"
     action(java_srcjar_target_name) {
       script = "//mojo/public/tools/gn/zip.py"
       inputs = process_file_template(invoker.sources, generator_java_outputs)
@@ skipping 25 matching lines @@
         # //mojo/something:something and we can append "_java" to get the java
         # dependency name.
         full_name = get_label_info(d, "label_no_toolchain")
         deps += [ "${full_name}_java" ]
       }
 
       srcjar_deps = [ ":$java_srcjar_target_name" ]
     }
   }
 }