gin: Add out-of-line copy ctors for complex classes.

gin/dictionary.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_DICTIONARY_H_
 #define GIN_DICTIONARY_H_
 
 #include "gin/converter.h"
 #include "gin/gin_export.h"
 
 namespace gin {
 
 // Dictionary is useful when writing bindings for a function that either
 // receives an arbitrary JavaScript object as an argument or returns an
 // arbitrary JavaScript object as a result. For example, Dictionary is useful
 // when you might use the |dictionary| type in WebIDL:
 //
 //   http://heycam.github.io/webidl/#idl-dictionaries
 //
 // WARNING: You cannot retain a Dictionary object in the heap. The underlying
 //          storage for Dictionary is tied to the closest enclosing
 //          v8::HandleScope. Generally speaking, you should store a Dictionary
 //          on the stack.
 //
 class GIN_EXPORT Dictionary {
  public:
   explicit Dictionary(v8::Isolate* isolate);
   Dictionary(v8::Isolate* isolate, v8::Local<v8::Object> object);
+  Dictionary(const Dictionary& other);
   ~Dictionary();
 
   static Dictionary CreateEmpty(v8::Isolate* isolate);
 
   template<typename T>
   bool Get(const std::string& key, T* out) {
     v8::Local<v8::Value> val;
     if (!object_->Get(isolate_->GetCurrentContext(), StringToV8(isolate_, key))
              .ToLocal(&val)) {
       return false;
@@ skipping 27 matching lines @@
   static v8::Local<v8::Value> ToV8(v8::Isolate* isolate,
                                     Dictionary val);
   static bool FromV8(v8::Isolate* isolate,
                      v8::Local<v8::Value> val,
                      Dictionary* out);
 };
 
 }  // namespace gin
 
 #endif  // GIN_DICTIONARY_H_