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

src/plugin/PluginClass.h

 /*
  * 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 121 matching lines @@
   void STDMETHODCALLTYPE OnDocumentComplete(IDispatch* frameBrowserDisp, VARIANT* /*urlOrPidl*/);
   void STDMETHODCALLTYPE OnWindowStateChanged(unsigned long flags, unsigned long validFlagsMask);
   void STDMETHODCALLTYPE OnCommandStateChange(long command, VARIANT_BOOL enable);
   void STDMETHODCALLTYPE OnOnQuit();
   void Unadvise();
 
   void ShowStatusBar();
   bool IsStatusBarEnabled();
 
   /**
-   * Our site object as a browser.
+   * A browser interface pointer to our site object
    *
    * It's values are set and reset solely in SetSite().

[sergei, 2015/11/30 15:52:09]

This part of the comment is not necessary, it's clear from the aim of
ATL::CComPtr.

[Eric, 2015/11/30 16:31:51]

I disagree. Nothing about this variable is either clear or obvious.

[Oleksandr, 2015/12/03 11:51:58]

I assume we're talking about the part of the comment below, not above. I agree
it looks redundant - CComPtr usage is always a defensive programming. But this
being just a comment I don't mind leaving it here.

[Eric, 2015/12/03 14:24:54]

It's no more defensive, at least ordinarily, than using 'unique_ptr' or
'shared_ptr' is.

In the present case it's compensating for a poor interface design in SetSite(),
which takes an 'IUnknown*' and contains no further type information, even though
it's always present in the caller.

I've edited down the comment.

-   * The declaration as CComPtr is defensive programming;
-   *   it ensures that the site keeps this interface alive for us in the
-   *   unlikely case that the site is different from a browser.
    */
   CComPtr<IWebBrowser2> m_webBrowser2;
   HWND m_hBrowserWnd;
   HWND m_hTabWnd;
   HWND m_hStatusBarWnd;
   HWND m_hPaneWnd;
   
   WNDPROC m_pWndProcStatus;
   int m_nPaneWidth;
   HANDLE m_hTheme;
@@ skipping 28 matching lines @@
 
   // Async browser
   static CComQIPtr<IWebBrowser2> s_asyncWebBrowser2;
   static CComQIPtr<IWebBrowser2> GetAsyncBrowser();
 };
 
 OBJECT_ENTRY_AUTO(__uuidof(PluginClass), CPluginClass)
 
 
 #endif // _PLUGIN_CLASS_H_