Issue #2230, #3391 - Load filters on "download begin" event

src/plugin/PluginClass.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 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 500 matching lines @@
       DEBUG_NAVI(L"Navi::Begin navigation url:" + url)
       m_tab->CacheFrame(url);
     }
   }
   catch (...)
   {
   }
 }
 
 // Entry point
+void STDMETHODCALLTYPE CPluginClass::OnDownloadBegin()
+{
+  try
+  {
+    DEBUG_NAVI("OnDownloadBegin");
+    m_tab->OnDownloadBegin();
+  }
+  catch (...)
+  {
+  }
+}
+
+// Entry point
 void STDMETHODCALLTYPE CPluginClass::OnDownloadComplete()
 {
   try
   {
     if (!m_webBrowser2)
     {
       DEBUG_ERROR_LOG(0, 0, 0, "CPluginClass::OnDownloadComplete - Reached with m_webBrowser2 == nullptr");
       return;
     }
     DEBUG_NAVI(L"Navi::Download Complete")
@@ skipping 1176 matching lines @@
   s_criticalSectionLocal.Unlock();
 
   return icon;
 }
 
 ATOM CPluginClass::GetAtomPaneClass()
 {
   return s_atomPaneClass;
 }