Added impersonation of the anonymous token around CloseClipboard

remoting/host/clipboard_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "remoting/host/clipboard.h"
 
 #include <windows.h>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
@@ skipping 14 matching lines @@
 // A scoper class that opens and closes the clipboard.
 // This class was adapted from the ScopedClipboard class in
 // ui/base/clipboard/clipboard_win.cc.
 class ScopedClipboard {
  public:
   ScopedClipboard() : opened_(false) {
   }
 
   ~ScopedClipboard() {
     if (opened_) {
+      ::ImpersonateAnonymousToken(GetCurrentThread());

[jschuh, 2014/12/11 17:53:06]

I know the impersonate *shouldn't* fail, but it's best to catch it regardless.
So, something like:

  BOOL shouldRevert = ::ImpersonateAnonymousToken(GetCurrentThread());
  DCHECK(shouldRevert);
  ::CloseClipboard();
  if (shouldRevert)
    ::RevertToSelf();

[dcheng, 2014/12/11 18:18:23]

Can we use a scoper to wrap this logic?
... also, unrelated but... what is this API even used for?

       ::CloseClipboard();
+      ::RevertToSelf();
     }
   }
 
   bool Init(HWND owner) {
     const int kMaxAttemptsToOpenClipboard = 5;
     const base::TimeDelta kSleepTimeBetweenAttempts =
         base::TimeDelta::FromMilliseconds(5);
 
     if (opened_) {
       NOTREACHED();
@@ skipping 223 matching lines @@
   }
 
   return false;
 }
 
 scoped_ptr<Clipboard> Clipboard::Create() {
   return make_scoped_ptr(new ClipboardWin());
 }
 
 }  // namespace remoting