Issue 4938 - fix race conditions related to LazyFileSystem

test/UpdateCheck.cpp

 /*
  * 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
@@ skipping 37 matching lines @@
     void SetUp()
     {
       eventCallbackCalled = false;
       updateCallbackCalled = false;
     }
 
     void CreateFilterEngine()
     {
       JsEngineCreationParameters jsEngineParams;
       jsEngineParams.appInfo = appInfo;
+      LazyFileSystem* fileSystem;
       jsEngineParams.logSystem.reset(new LazyLogSystem());
-      jsEngineParams.fileSystem.reset(new LazyFileSystem());
+      jsEngineParams.fileSystem.reset(fileSystem = new LazyFileSystem());
       jsEngineParams.timer = DelayedTimer::New(timerTasks);
       jsEngineParams.webRequest = DelayedWebRequest::New(webRequestTasks);
       auto jsEngine = CreateJsEngine(std::move(jsEngineParams));
       jsEngine->SetEventCallback("updateAvailable", [this](JsValueList&& params)
       {
         eventCallbackCalled = true;
         eventCallbackParams = std::move(params);
       });
 
-      filterEngine = AdblockPlus::FilterEngine::Create(jsEngine);
+      filterEngine = ::CreateFilterEngine(*fileSystem, jsEngine);
     }
 
     // Returns a URL or the empty string if there is no such request.
     std::string ProcessPendingUpdateWebRequest()
     {
       auto ii = webRequestTasks->begin();
       while (ii != webRequestTasks->end())
       {
         if (ii->url.find("update.json") != std::string::npos)
         {
@@ skipping 219 matching lines @@
 
   // ensure that the was the corresponding request
   EXPECT_FALSE(ProcessPendingUpdateWebRequest().empty());
 
   EXPECT_FALSE(eventCallbackCalled);
   EXPECT_EQ(1, timesCalled);
 
   // previous handler is not restored
   EXPECT_FALSE(eventCallbackCalled);
 }