Issue 5569 - add the possibility to use synchronous WebRequest and base path in File System

include/AdblockPlus/IWebRequest.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 96 matching lines @@
      * @param requestHeaders Request headers.
      * @param getCallback to invoke when the server response is ready.
      */
     virtual void GET(const std::string& url, const HeaderList& requestHeaders, const GetCallback& getCallback) = 0;
   };
 
   /**
    * Unique smart pointer to an instance of `IWebRequest` implementation.
    */
   typedef std::unique_ptr<IWebRequest> WebRequestPtr;
+
+
+  /**
+   * Private functionality.
+   */
+  struct IWebRequestSync
+  {
+    virtual ~IWebRequestSync() {}
+    virtual ServerResponse GET(const std::string& url, const HeaderList& requestHeaders) const = 0;
+  };
+  typedef std::unique_ptr<IWebRequestSync> WebRequestSyncPtr;
 }
 
 #endif