Fix shutdown crash in CertVerifier by using a MessageLoopProxy.

base/message_loop_proxy_impl.cc

 // 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.
 
 #include "base/message_loop_proxy_impl.h"
 #include "base/thread_restrictions.h"
 
 namespace base {
 
 MessageLoopProxyImpl::MessageLoopProxyImpl()
@@ skipping 60 matching lines @@
       }
       ret = true;
     }
   }
   if (!ret)
     delete task;
   return ret;
 }
 
 void MessageLoopProxyImpl::OnDestruct() const {
+  // We shouldn't use MessageLoop::current() since it uses LazyInstance which
+  // may be deleted by ~AtExitManager when a WorkerPool thread calls this
+  // function.
+  // http://crbug.com/63678
+  base::ThreadRestrictions::ScopedAllowSingleton allow_singleton;
   bool delete_later = false;
   {
     AutoLock lock(message_loop_lock_);
     if (target_message_loop_ &&
         (MessageLoop::current() != target_message_loop_)) {
       target_message_loop_->DeleteSoon(FROM_HERE, this);
       delete_later = true;
     }
   }
   if (!delete_later)
     delete this;
 }
 
 // MessageLoop::DestructionObserver implementation
 void MessageLoopProxyImpl::WillDestroyCurrentMessageLoop() {
   AutoLock lock(message_loop_lock_);
   target_message_loop_ = NULL;
 }
 
 scoped_refptr<MessageLoopProxy>
 MessageLoopProxy::CreateForCurrentThread() {
   scoped_refptr<MessageLoopProxy> ret(new MessageLoopProxyImpl());
   return ret;
 }
 
 }  // namespace base