refactor: EventEmitters without gin_helper (#22726)

shell/browser/event_emitter_mixin.cc

@@ -0,0 +1,45 @@
+// Copyright (c) 2019 Slack Technologies, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#include "shell/browser/event_emitter_mixin.h"
+
+#include "gin/public/wrapper_info.h"
+#include "shell/browser/api/electron_api_event_emitter.h"
+
+namespace gin_helper {
+
+namespace internal {
+
+gin::WrapperInfo kWrapperInfo = {gin::kEmbedderNativeGin};
+
+v8::Local<v8::FunctionTemplate> GetEventEmitterTemplate(v8::Isolate* isolate) {
+  gin::PerIsolateData* data = gin::PerIsolateData::From(isolate);
+  v8::Local<v8::FunctionTemplate> tmpl =
+      data->GetFunctionTemplate(&kWrapperInfo);
+
+  if (tmpl.IsEmpty()) {
+    tmpl = v8::FunctionTemplate::New(isolate);
+    v8::Local<v8::Context> context = isolate->GetCurrentContext();
+    v8::Local<v8::Function> func = tmpl->GetFunction(context).ToLocalChecked();
+
+    v8::Local<v8::Object> eventemitter_prototype =
+        electron::GetEventEmitterPrototype(isolate);
+
+    v8::Local<v8::Value> func_prototype;
+    CHECK(func->Get(context, gin::StringToSymbol(isolate, "prototype"))
+              .ToLocal(&func_prototype));
+
+    CHECK(func_prototype.As<v8::Object>()
+              ->SetPrototype(context, eventemitter_prototype)
+              .ToChecked());
+
+    data->SetFunctionTemplate(&kWrapperInfo, tmpl);
+  }
+
+  return tmpl;
+}
+
+}  // namespace internal
+
+}  // namespace gin_helper