bindings: Add C++ versions of WebIDL types and generalize NativeValueTraits.

third_party/WebKit/Source/bindings/templates/callback_function.cpp.tmpl

Index: third_party/WebKit/Source/bindings/templates/callback_function.cpp.tmpl
diff --git a/third_party/WebKit/Source/bindings/templates/callback_function.cpp.tmpl b/third_party/WebKit/Source/bindings/templates/callback_function.cpp.tmpl
index ccf2c5d782c48881e86f51e95972dcb01bea7ae9..def34ae745b35433cc3fa9788fe06de4c50002a2 100644
--- a/third_party/WebKit/Source/bindings/templates/callback_function.cpp.tmpl
+++ b/third_party/WebKit/Source/bindings/templates/callback_function.cpp.tmpl
@@ -74,6 +74,10 @@ bool {{cpp_class}}::call({{argument_declarations | join(', ')}}) {
   return false;
 }
 
+{{cpp_class}}* NativeValueTraits<{{cpp_class}}>::nativeValue(v8::Isolate* isolate, v8::Local<v8::Value> value, ExceptionState& exceptionState) {
+  return {{cpp_class}}::create(ScriptState::current(isolate), value);

[haraken, 2017/03/06 12:56:33]

If this nativeValue() is expected to be not used, we can add NOT_REACHED().

[Raphael Kubo da Costa (rakuco), 2017/03/06 14:29:17]

I don't think there's anything preventing callback functions from being used in
records, which is why this was added in the first place. If that's not the case,
it makes more sense to remove this NativeValueTraits specialization altogether.

+}
+
 }  // namespace blink
 
 {% endfilter %}{# format_blink_cpp_source_code #}