Issue #1652, #3456 - Replace 's_asyncWebBrowser2' with thread-safe facilities

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 10 matching lines @@
 
 #ifndef _PLUGIN_CLASS_H_
 #define _PLUGIN_CLASS_H_
 
 
 #include "Plugin.h"
 #include "PluginTabBase.h"
 #define _CRTDBG_MAP_ALLOC
 #include <stdlib.h>
 #include <crtdbg.h>
-#include <set>
+#include <mutex>
 
 #include "NotificationMessage.h"
 
 #define ICON_PLUGIN_DISABLED 0
 #define ICON_PLUGIN_ENABLED 1
 #define ICON_PLUGIN_DEACTIVATED 2
 #define ICON_MAX 3
 
 #define WM_LAUNCH_INFO                                  (WM_APP + 10)
 
 class CPluginMimeFilterClient;
 
 
 class ATL_NO_VTABLE CPluginClass :
   public ATL::CComObjectRootEx<ATL::CComMultiThreadModel>,
   public ATL::CComCoClass<CPluginClass, &CLSID_PluginClass>,
   public ATL::IObjectWithSiteImpl<CPluginClass>,
   public IOleCommandTarget,
   public ATL::IDispEventImpl<1, CPluginClass, &DIID_DWebBrowserEvents2, &LIBID_SHDocVw, 1, 1>
 {
 
   friend class CPluginTab;
+  friend class AnyCurrentSiteBrowser;
 
 private:
 
   CPluginTab* m_tab;
 
 public:
 
   DECLARE_REGISTRY_RESOURCEID(IDR_PLUGIN_CLASS)
 
   DECLARE_PROTECT_FINAL_CONSTRUCT()
@@ skipping 32 matching lines @@
 
   bool SetMenuBar(HMENU hMenu, const std::wstring& url);
   HMENU CreatePluginMenu(const std::wstring& url);
 
   void DisplayPluginMenu(HMENU hMenu, int nToolbarCmdID, POINT pt, UINT nMenuFlags);
   bool CreateStatusBarPane();
 
 public:
   HWND GetBrowserHWND() const;
   bool IsRootBrowser(IWebBrowser2*);
-
   static CPluginMimeFilterClient* s_mimeFilter;
 
 private:
 
   std::wstring GetBrowserUrl() const;
 
   static DWORD WINAPI StartInitObject(LPVOID thisPtr);
   bool InitObject();
   void CloseTheme();
   void UpdateTheme();
@@ skipping 12 matching lines @@
                                            VARIANT* Headers /**< [in] */,
                                            VARIANT_BOOL* Cancel /* [in, out] */);
   void STDMETHODCALLTYPE OnDownloadComplete();
   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();
 
   /**
    * A browser interface pointer to our site object
    *
    * It's values are set and reset solely in SetSite().
    */
   CComPtr<IWebBrowser2> m_webBrowser2;
+  /**
+   * Synchronizes SetSite() with references to our site pointer.

[sergei, 2016/01/04 15:34:31]

I would like to have here a little bit extended comment that it can be used, for
example, to avoid any wrong usage of injected objects beyond the time span
between SetSite(not nullptr) and SetSite(nullptr). For example,
AnyCurrentSiteBrowser helps to  achieve it.

[Eric, 2016/01/04 17:49:20]

There's nothing I could add here that's not fully explained in the
already-extensive comments for 'AnyCurrentSiteBrowser'.

The term "synchronizes with" is jargon from the C++ language standard. I'm
assuming a reader knows that. With that in mind, the comment completely explains
what this member variable does.

You seem to be looking for "how it's used" comments, but those are elsewhere.

+   */
+  std::mutex siteGuard;
+
   HWND m_hBrowserWnd;
   HWND m_hTabWnd;
   HWND m_hStatusBarWnd;
   HWND m_hPaneWnd;
   
   WNDPROC m_pWndProcStatus;
   int m_nPaneWidth;
   HANDLE m_hTheme;
 
   CriticalSection m_csStatusBar;
@@ skipping 12 matching lines @@
   static HICON s_hIcons[ICON_MAX];
   static DWORD s_hIconTypes[ICON_MAX];
 
   static HICON GetIcon(int type);
 
   // Main thread
   static HANDLE s_hMainThread;
   static bool s_isMainThreadDone;
 
   static HINSTANCE s_hUxtheme;
-  static std::set<CPluginClass*> s_instances;
   static std::map<DWORD,CPluginClass*> s_threadInstances;
   static CComAutoCriticalSection s_criticalSectionLocal;
   static CComAutoCriticalSection s_criticalSectionWindow;
-
-  // Async browser
-  static CComQIPtr<IWebBrowser2> s_asyncWebBrowser2;
-  static CComQIPtr<IWebBrowser2> GetAsyncBrowser();
 };
 
 OBJECT_ENTRY_AUTO(__uuidof(PluginClass), CPluginClass)
 
 
 #endif // _PLUGIN_CLASS_H_