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

mojo/mojom_bindings_generator.gypi

Index: mojo/mojom_bindings_generator.gypi
diff --git a/mojo/mojom_bindings_generator.gypi b/mojo/mojom_bindings_generator.gypi
index 3b2e1bb12b094f11e9b3940937c70558f0546747..6518ee4c66e1633d6433980ae3971ec37da76751 100644
--- a/mojo/mojom_bindings_generator.gypi
+++ b/mojo/mojom_bindings_generator.gypi
@@ -11,10 +11,12 @@
       'mojom_typemap_dependencies%': [],
       'mojom_typemaps%': [],
       'mojom_variant%': 'none',
+      'for_blink%': 'false',
     },
     'mojom_typemap_dependencies%': ['<@(mojom_typemap_dependencies)'],
     'mojom_typemaps%': ['<@(mojom_typemaps)'],
     'mojom_variant%': '<(mojom_variant)',
+    'for_blink%': '<(for_blink)',
     'mojom_base_output_dir':
         '<!(python <(DEPTH)/build/inverse_depth.py <(DEPTH))',
     'mojom_generated_outputs': [
@@ -30,6 +32,18 @@
       }, {
         'mojom_output_languages%': 'c++',
       }],
+      ['for_blink=="true"', {
+        'mojom_generator_wtf_arg%': [
+          '--for_blink',
+        ],
+        'wtf_dependencies%': [
+          'mojo_public.gyp:mojo_cpp_bindings_wtf_support',
+          '../third_party/WebKit/Source/wtf/wtf.gyp:wtf',
+        ],
+      }, {
+        'mojom_generator_wtf_arg%': [],
+        'wtf_dependencies%': [],
+      }],
     ],
   },
   'actions': [
@@ -98,6 +112,7 @@
         '-g', '<(mojom_output_languages)',
         '<@(mojom_generator_typemap_args)',
         '<@(mojom_extra_generator_args)',
+        '<@(mojom_generator_wtf_arg)',
         '--bytecode_path',
         '<(SHARED_INTERMEDIATE_DIR)/mojo/public/tools/bindings',
       ],
@@ -110,9 +125,11 @@
     '<(DEPTH)/mojo/mojo_public.gyp:mojo_interface_bindings_generation',
     '<(DEPTH)/mojo/public/tools/bindings/bindings.gyp:precompile_mojom_bindings_generator_templates',
     '<@(mojom_typemap_dependencies)',
+    '<@(wtf_dependencies)',
   ],
   'export_dependent_settings': [
     '<@(mojom_typemap_dependencies)',
+    '<@(wtf_dependencies)',
   ],
   'include_dirs': [
     '<(DEPTH)',