Fix shutdown crash in CertVerifier by using a MessageLoopProxy.

base/message_loop_proxy.h

 // Copyright (c) 2010 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.
 
 #ifndef BASE_MESSAGE_LOOP_PROXY_H_
 #define BASE_MESSAGE_LOOP_PROXY_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/ref_counted.h"
 #include "base/task.h"
 
 namespace base {
 
 struct MessageLoopProxyTraits;
 
 // This class provides a thread-safe refcounted interface to the Post* methods
 // of a message loop. This class can outlive the target message loop. You can
-// obtain a MessageLoopProxy via Thread::message_loop_proxy().
+// obtain a MessageLoopProxy via Thread::message_loop_proxy() or
+// MessageLoopProxy::CreateForCurrentThread().
 class MessageLoopProxy
     : public base::RefCountedThreadSafe<MessageLoopProxy,
                                         MessageLoopProxyTraits> {
  public:
   // These methods are the same as in message_loop.h, but are guaranteed to
   // either post the Task to the MessageLoop (if it's still alive), or to
   // delete the Task otherwise.
   // They return true iff the thread existed and the task was posted.  Note that
   // even if the task is posted, there's no guarantee that it will run, since
   // the target thread may already have a Quit message in its queue.
@@ skipping 39 matching lines @@
 
 struct MessageLoopProxyTraits {
   static void Destruct(const MessageLoopProxy* proxy) {
     proxy->OnDestruct();
   }
 };
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_PROXY_H_