Issue #3383 - Rewrite and simplify browser-site handling in CPluginClass

src/plugin/PluginClass.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2015 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 104 matching lines @@
   delete m_tab;
 }
 
 HWND CPluginClass::GetBrowserHWND() const
 {
   if (!m_webBrowser2)
   {
     DEBUG_ERROR_LOG(0, 0, 0, "CPluginClass::GetBrowserHWND - Reached with m_webBrowser2 == nullptr");
     return nullptr;
   }
-  SHANDLE_PTR hBrowserWndHandle;
+  SHANDLE_PTR hBrowserWndHandle = 0;
   HRESULT hr = m_webBrowser2->get_HWND(&hBrowserWndHandle);
   if (FAILED(hr))
   {
     DEBUG_ERROR_LOG(hr, PLUGIN_ERROR_UI, PLUGIN_ERROR_UI_GET_BROWSER_WINDOW, "Class::GetBrowserHWND - failed");
     return nullptr;
   }
   return (HWND)hBrowserWndHandle;
 }
 
 bool CPluginClass::IsRootBrowser(IWebBrowser2* otherBrowser)
@@ skipping 1497 matching lines @@
   s_criticalSectionLocal.Unlock();
 
   return icon;
 }
 
 ATOM CPluginClass::GetAtomPaneClass()
 {
   return s_atomPaneClass;
 }