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

remoting/protocol/v2_authenticator.cc

Index: remoting/protocol/v2_authenticator.cc
diff --git a/remoting/protocol/v2_authenticator.cc b/remoting/protocol/v2_authenticator.cc
index d1d9f56c1f0146ebcca2b1e4ba5cc27f361dc04a..ab2335dd5745d5ab029cc9cd95a001bf517d64cb 100644
--- a/remoting/protocol/v2_authenticator.cc
+++ b/remoting/protocol/v2_authenticator.cc
@@ -79,7 +79,13 @@ Authenticator::RejectionReason V2Authenticator::rejection_reason() const {
   return rejection_reason_;
 }
 
-void V2Authenticator::ProcessMessage(const buzz::XmlElement* message) {
+void V2Authenticator::ProcessMessage(const base::Closure& resume_callback,
+                                     const buzz::XmlElement* message) {
+  ProcessMessageInternal(message);
+  resume_callback.Run();
+}
+
+void V2Authenticator::ProcessMessageInternal(const buzz::XmlElement* message) {
   DCHECK_EQ(state(), WAITING_MESSAGE);
 
   // Parse the certificate.