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

mojo/mojo_public.gyp

Index: mojo/mojo_public.gyp
diff --git a/mojo/mojo_public.gyp b/mojo/mojo_public.gyp
index 6490657f33a3d3e2f83d54751417938468bff88e..2de5dcfc634f50879f8cd80a5bbd977b751bdeb3 100644
--- a/mojo/mojo_public.gyp
+++ b/mojo/mojo_public.gyp
@@ -175,6 +175,9 @@
         'public/cpp/bindings/lib/validation_util.cc',
         'public/cpp/bindings/lib/validation_util.h',
         'public/cpp/bindings/lib/value_traits.h',
+        # Include the .h but not the .cc file. The .h file is used by
+        # serialization_forward.h.
+        'public/cpp/bindings/lib/wtf_string_serialization.h',
         'public/cpp/bindings/message.h',
         'public/cpp/bindings/message_filter.h',
         'public/cpp/bindings/no_interface.h',
@@ -191,6 +194,28 @@
       ],
     },
     {
+      # GN version: //mojo/public/cpp/bindings:wtf_support
+      'target_name': 'mojo_cpp_bindings_wtf_support',
+      'type': 'static_library',
+      'include_dirs': [
+        '..'
+      ],
+      'sources': [
+        'public/cpp/bindings/lib/wtf_serialization.h',
+        'public/cpp/bindings/lib/wtf_string_serialization.cc',
+        'public/cpp/bindings/lib/wtf_string_serialization.h',
+      ],
+      'dependencies': [
+        'mojo_cpp_bindings',
+        '../third_party/WebKit/Source/config.gyp:config',
+        '../third_party/WebKit/Source/wtf/wtf.gyp:wtf',
+      ],
+      'export_dependent_settings': [
+        'mojo_cpp_bindings',
+        '../third_party/WebKit/Source/config.gyp:config',
+      ],
+    },
+    {
       # GN version: //mojo/message_pump
       'target_name': 'mojo_message_pump_lib',
       'type': '<(component)',
@@ -512,6 +537,27 @@
         'mojo_cpp_bindings',
       ],
     },
+    {
+      'target_name': 'mojo_public_test_wtf_types',
+      'type': 'static_library',
+      'sources': [
+        'public/interfaces/bindings/tests/test_wtf_types.mojom',
+      ],
+      'includes': [ 'mojom_bindings_generator.gypi' ],
+    },
+    {
+      'target_name': 'mojo_public_test_wtf_types_wtf',
+      'type': 'static_library',
+      'variables': {
+        'mojom_variant': 'wtf',
+        'use_wtf_types': 'true',
+      },
+      'sources': [
+        'public/interfaces/bindings/tests/test_wtf_types.mojom',
+      ],
+      'includes': [ 'mojom_bindings_generator.gypi' ],
+      'dependencies': [ 'mojo_public_test_wtf_types' ],
+    },
   ],
   'conditions': [
     ['OS == "android"', {