void setBufferCallback(Evas_Object* webview);
void unsetBufferCallback(Evas_Object* webview);
void decideNavigationCallback(Evas_Object* webview, std::string& uri);
void setBufferCallback(Evas_Object* webview);
void unsetBufferCallback(Evas_Object* webview);
void decideNavigationCallback(Evas_Object* webview, std::string& uri);