Refactor of Authenticator to allow it to ProcessMessage asynchronously and then call a callback

remoting/host/pam_authorization_factory_posix.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/pam_authorization_factory_posix.h"
 
 #include <security/pam_appl.h>
 
+#include "base/bind.h"
+#include "base/callback.h"
 #include "base/environment.h"
 #include "base/logging.h"
 #include "remoting/protocol/channel_authenticator.h"
 #include "third_party/libjingle/source/talk/xmllite/xmlelement.h"
 
 namespace remoting {
 
 namespace {
 class PamAuthorizer : public protocol::Authenticator {
  public:
   PamAuthorizer(scoped_ptr<protocol::Authenticator> underlying);
   virtual ~PamAuthorizer();
 
   // protocol::Authenticator interface.
   virtual State state() const OVERRIDE;
   virtual RejectionReason rejection_reason() const OVERRIDE;
-  virtual void ProcessMessage(const buzz::XmlElement* message) OVERRIDE;
+  virtual void ProcessMessage(const base::Closure& resume_callback,
+                              const buzz::XmlElement* message) OVERRIDE;
   virtual scoped_ptr<buzz::XmlElement> GetNextMessage() OVERRIDE;
   virtual scoped_ptr<protocol::ChannelAuthenticator>
       CreateChannelAuthenticator() const OVERRIDE;
 
  private:
   void MaybeCheckLocalLogin();
   bool IsLocalLoginAllowed();
+  void OnMessageProcessed(const base::Closure& resume_callback);
 
   static int PamConversation(int num_messages,
                              const struct pam_message** messages,
                              struct pam_response** responses,
                              void* context);
 
   scoped_ptr<protocol::Authenticator> underlying_;
   enum { NOT_CHECKED, ALLOWED, DISALLOWED } local_login_status_;
 };
 }  // namespace
@@ skipping 16 matching lines @@
 
 protocol::Authenticator::RejectionReason
 PamAuthorizer::rejection_reason() const {
   if (local_login_status_ == DISALLOWED) {
     return INVALID_CREDENTIALS;
   } else {
     return underlying_->rejection_reason();
   }
 }
 
-void PamAuthorizer::ProcessMessage(const buzz::XmlElement* message) {
-  underlying_->ProcessMessage(message);
+void PamAuthorizer::ProcessMessage(const base::Closure& resume_callback,
+                                   const buzz::XmlElement* message) {
+  underlying_->ProcessMessage(base::Bind(
+      &PamAuthorizer::OnMessageProcessed,
+      // underlying is owned by PamAuthorizer and cannot outlive it.
+      base::Unretained(this), resume_callback), message);
+}
+
+void PamAuthorizer::OnMessageProcessed(const base::Closure& resume_callback) {
   MaybeCheckLocalLogin();
+  resume_callback.Run();
 }
 
 scoped_ptr<buzz::XmlElement> PamAuthorizer::GetNextMessage() {
-  scoped_ptr<buzz::XmlElement> result (underlying_->GetNextMessage());
+  scoped_ptr<buzz::XmlElement> result(underlying_->GetNextMessage());
   MaybeCheckLocalLogin();
   return result.Pass();
 }
 
 scoped_ptr<protocol::ChannelAuthenticator>
 PamAuthorizer::CreateChannelAuthenticator() const {
   return underlying_->CreateChannelAuthenticator();
 }
 
 void PamAuthorizer::MaybeCheckLocalLogin() {
@@ skipping 67 matching lines @@
     const std::string& remote_jid,
     const buzz::XmlElement* first_message) {
   scoped_ptr<protocol::Authenticator> authenticator(
       underlying_->CreateAuthenticator(local_jid, remote_jid, first_message));
   return scoped_ptr<protocol::Authenticator>(
       new PamAuthorizer(authenticator.Pass()));
 }
 
 
 }  // namespace remoting