Issue 4938 - fix race conditions and get rid of hacks related to DefaultFileSystem

src/DefaultFileSystem.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #ifndef ADBLOCK_PLUS_DEFAULT_FILE_SYSTEM_H
 #define ADBLOCK_PLUS_DEFAULT_FILE_SYSTEM_H
 
 #include <AdblockPlus/IFileSystem.h>
+#include <AdblockPlus/Scheduler.h>
 
 #ifdef _WIN32
 #define PATH_SEPARATOR '\\'
 #else
 #define PATH_SEPARATOR '/'
 #endif
 
 namespace AdblockPlus
 {
   /**
@@ skipping 18 matching lines @@
      */
     void SetBasePath(const std::string& path);
 
   protected:
     std::string basePath;
   };
 
   class DefaultFileSystem : public IFileSystem
   {
   public:
-    explicit DefaultFileSystem(std::unique_ptr<DefaultFileSystemSync> syncImpl);
+    explicit DefaultFileSystem(const Scheduler& scheduler, std::unique_ptr<DefaultFileSystemSync> syncImpl);
     void Read(const std::string& path,
               const ReadCallback& callback) const;
     void Write(const std::string& path,
                const IOBuffer& data,
                const Callback& callback);
     void Move(const std::string& fromPath,
               const std::string& toPath,
               const Callback& callback);
     void Remove(const std::string& path, const Callback& callback);
     void Stat(const std::string& path,
               const StatCallback& callback) const;
 
     std::string Resolve(const std::string& path) const;
   private:
+    Scheduler scheduler;
     std::unique_ptr<DefaultFileSystemSync> syncImpl;
   };
 }
 
 #endif