Cache locally function templates returned by gin::CreateFunctionTemplate

extensions/renderer/guest_view/mime_handler_view/mime_handler_view_container.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/renderer/guest_view/mime_handler_view/mime_handler_view_container.h"
 
 #include <map>
 #include <set>
 
 #include "content/public/child/v8_value_converter.h"
@@ skipping 32 matching lines @@
     ScriptableObject* scriptable_object =
         new ScriptableObject(isolate, container);
     return gin::CreateHandle(isolate, scriptable_object).ToV8()->ToObject();
   }
 
   // gin::NamedPropertyInterceptor
   v8::Local<v8::Value> GetNamedProperty(
       v8::Isolate* isolate,
       const std::string& identifier) override {
     if (identifier == kPostMessageName) {
-      return gin::CreateFunctionTemplate(isolate,
-          base::Bind(&MimeHandlerViewContainer::PostMessage,
-                     container_, isolate))->GetFunction();
+      if (post_message_function_template_.IsEmpty()) {
+        post_message_function_template_.Reset(
+            isolate,
+            gin::CreateFunctionTemplate(
+                isolate, base::Bind(&MimeHandlerViewContainer::PostMessage,
+                                    container_, isolate)));
+      }
+      return v8::Local<v8::FunctionTemplate>::New(
+                 isolate, post_message_function_template_)->GetFunction();
     }
     return v8::Local<v8::Value>();
   }
 
  private:
   ScriptableObject(v8::Isolate* isolate,
                    base::WeakPtr<MimeHandlerViewContainer> container)
     : gin::NamedPropertyInterceptor(isolate, this),
       container_(container) {}
 
   // gin::Wrappable
   gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
       v8::Isolate* isolate) override {
     return gin::Wrappable<ScriptableObject>::GetObjectTemplateBuilder(isolate)
         .AddNamedPropertyInterceptor();
   }
 
   base::WeakPtr<MimeHandlerViewContainer> container_;
+  v8::Persistent<v8::FunctionTemplate> post_message_function_template_;
 };
 
 // static
 gin::WrapperInfo ScriptableObject::kWrapperInfo = { gin::kEmbedderNativeGin };
 
 // Maps from content::RenderFrame to the set of MimeHandlerViewContainers within
 // it.
 base::LazyInstance<
     std::map<content::RenderFrame*, std::set<MimeHandlerViewContainer*>>>
     g_mime_handler_view_container_map = LAZY_INSTANCE_INITIALIZER;
@@ skipping 217 matching lines @@
 
   if (!render_frame())
     return;
 
   render_frame()->Send(new GuestViewHostMsg_CreateMimeHandlerViewGuest(
       render_frame()->GetRoutingID(), view_id_, element_instance_id(),
       element_size_));
 }
 
 }  // namespace extensions