Add missing (and remove superfluous) 'explicit' from constructors.

remoting/host/pam_authorization_factory_posix.h

 // 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.
 
 #ifndef REMOTING_HOST_PAM_AUTHORIZATION_FACTORY_POSIX_H_
 #define REMOTING_HOST_PAM_AUTHORIZATION_FACTORY_POSIX_H_
 
 #include "remoting/protocol/authenticator.h"
 
 #include "base/memory/scoped_ptr.h"
 
 // PamAuthorizationFactory abuses the AuthenticatorFactory interface to apply
 // PAM-based authorization on top of some underlying authentication scheme.
 
 namespace remoting {
 
 class PamAuthorizationFactory : public protocol::AuthenticatorFactory {
  public:
-  PamAuthorizationFactory(
+  explicit PamAuthorizationFactory(
       scoped_ptr<protocol::AuthenticatorFactory> underlying);
   virtual ~PamAuthorizationFactory();
 
   virtual scoped_ptr<protocol::Authenticator> CreateAuthenticator(
       const std::string& local_jid,
       const std::string& remote_jid,
       const buzz::XmlElement* first_message) OVERRIDE;
 
  private:
   scoped_ptr<protocol::AuthenticatorFactory> underlying_;
 };
 
 }  // namespace remoting
 
 #endif