[Gin] Add Arguments::GetHolderCreationContext()

gin/arguments.h

 // Copyright 2013 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.
 
 #ifndef GIN_ARGUMENTS_H_
 #define GIN_ARGUMENTS_H_
 
 #include "gin/converter.h"
 #include "gin/gin_export.h"
 
@@ skipping 56 matching lines @@
   }
 
   template<typename T>
   void Return(T val) {
     v8::Local<v8::Value> v8_value;
     if (!TryConvertToV8(isolate_, val, &v8_value))
       return;
     info_->GetReturnValue().Set(v8_value);
   }
 
+  // Returns the creation context of the Holder.
+  v8::Local<v8::Context> GetHolderCreationContext();
+
   // Always check the return value whether the handle is empty before
   // dereferencing the handle.
   v8::Local<v8::Value> PeekNext() const;
 
   void ThrowError() const;
   void ThrowTypeError(const std::string& message) const;
 
   v8::Isolate* isolate() const { return isolate_; }
 
   // Allows the function handler to distinguish between normal invocation
   // and object construction.
   bool IsConstructCall() const;
 
  private:
   v8::Isolate* isolate_;
   const v8::FunctionCallbackInfo<v8::Value>* info_;
   int next_;
   bool insufficient_arguments_;
 };
 
 }  // namespace gin
 
 #endif  // GIN_ARGUMENTS_H_