WIP: Create a LongStringCollection that transfers long strings with fewer copies.

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

 {% from 'utilities.cpp.tmpl' import declare_enum_validation_variable, v8_value_to_local_cpp_value %}
 
 {##############################################################################}
 {% macro generate_method(method, world_suffix) %}
 static void {{method.name}}{{method.overload_index}}Method{{world_suffix}}(const v8::FunctionCallbackInfo<v8::Value>& info) {
   {% filter format_remove_duplicates([
       'ExceptionState exceptionState',
       'ScriptState* scriptState = ']) %}
   {% set define_exception_state -%}
   ExceptionState exceptionState(info.GetIsolate(), ExceptionState::ExecutionContext, "{{interface_name}}", "{{method.name}}");
@@ skipping 417 matching lines @@
     if (!SerializedScriptValue::extractTransferables(info.GetIsolate(), info[transferablesArgIndex], transferablesArgIndex, transferables, exceptionState)) {
       return;
     }
   }
 
   RefPtr<SerializedScriptValue> message;
   if (instance->canTransferArrayBuffersAndImageBitmaps()) {
     // This instance supports sending array buffers by move semantics.
     SerializedScriptValue::SerializeOptions options;
     options.transferables = &transferables;
+    options.longStringPolicy = LongStringPolicy(LongStringPolicy::kSameProcess, 512);
     message = SerializedScriptValue::serialize(info.GetIsolate(), info[0], options, exceptionState);
     if (exceptionState.hadException())
       return;
   } else {
     // This instance doesn't support sending array buffers and image bitmaps
     // by move semantics. Emulate it by copy-and-neuter semantics that sends
     // array buffers and image bitmaps via structured clone and then neuters
     // the original objects
 
     // Clear references to array buffers and image bitmaps from transferables
@@ skipping 196 matching lines @@
   {{method_configuration(method) | indent(2)}}
 };
 for (const auto& methodConfig : {{method.name}}MethodConfiguration)
   V8DOMConfiguration::installMethod(isolate, world, v8::Local<v8::Object>(), prototypeObject, interfaceObject, signature, methodConfig);
 {% endfilter %}{# runtime_enabled() #}
 {% endfilter %}{# exposed() #}
 {% endfilter %}{# secure_context() #}
 {% endfor %}
 {% endif %}
 {%- endmacro %}