Issue 5182, 4688 - improve IsSubscriptionDowloadAllowedCallback and corresponding tests

include/AdblockPlus/FilterEngine.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
@@ skipping 237 matching lines @@
      */
     typedef std::map<std::string, AdblockPlus::JsValue> Prefs;
 
     /**
      * Callback type invoked when a new notification should be shown.
      * The parameter is the Notification object to be shown.
      */
     typedef std::function<void(Notification&&)> ShowNotificationCallback;
 
     /**
-     * Callback function returning false when current connection is not
-     * allowedConnectionType, e.g. because it is a metered connection.
+     * Asynchronous callback function passing false when current connection
+     * type does not correspond to allowedConnectionType, e.g. because it is a
+     * metered connection.
      */
-    typedef std::function<bool(const std::string* allowedConnectionType)> IsConnectionAllowedCallback;
+    typedef std::function<void(const std::string* allowedConnectionType, const std::function<void(bool)>&)> IsConnectionAllowedAsyncCallback;
 
     /**
      * FilterEngine creation parameters.
      */
     struct CreationParameters
     {
       /**
        * `AdblockPlus::FilterEngine::Prefs` name - value list of preconfigured
        * prefs.
        */
       Prefs preconfiguredPrefs;
       /**
-       * `AdblockPlus::FilterEngine::IsConnectionAllowedCallback` a callback
-       * checking whether the request from Adblock Plus should be blocked on
-       * the current connection.
+       * A callback of `AdblockPlus::FilterEngine::IsConnectionAllowedAsyncCallback` type
+       * checking whether the request to download a subscription from Adblock Plus may be performed
+       * on the current connection.
        */
-      IsConnectionAllowedCallback isConnectionAllowedCallback;
+      IsConnectionAllowedAsyncCallback isSubscriptionDowloadAllowedCallback;
     };
 
     /**
     * Callback type invoked when FilterEngine is created.
     */
     typedef std::function<void(const FilterEnginePtr&)> OnCreatedCallback;
 
     /**
      * Asynchronously constructs FilterEngine.
      * @param jsEngine `JsEngine` instance used to run JavaScript code
@@ skipping 283 matching lines @@
     void FilterChanged(const FilterChangeCallback& callback, JsValueList&& params) const;
     FilterPtr GetWhitelistingFilter(const std::string& url,
       ContentTypeMask contentTypeMask, const std::string& documentUrl) const;
     FilterPtr GetWhitelistingFilter(const std::string& url,
       ContentTypeMask contentTypeMask,
       const std::vector<std::string>& documentUrls) const;
   };
 }
 
 #endif