Handle pairing_client_id in the negotiating authenticators.

remoting/protocol/negotiating_host_authenticator.h

Index: remoting/protocol/negotiating_host_authenticator.h
diff --git a/remoting/protocol/negotiating_host_authenticator.h b/remoting/protocol/negotiating_host_authenticator.h
index 2ba78d581d1f80da1beed1eff2294e3efcfecff4..25a761ed1db69d7a70fccce2f7daf6802fb7220f 100644
--- a/remoting/protocol/negotiating_host_authenticator.h
+++ b/remoting/protocol/negotiating_host_authenticator.h
@@ -71,7 +71,6 @@ class NegotiatingHostAuthenticator : public NegotiatingAuthenticatorBase {
   // (Asynchronously) creates an authenticator, and stores it in
   // |current_authenticator_|. Authenticators that can be started in either
   // state will be created in |preferred_initial_state|.
-  // |resume_callback| is called after |current_authenticator_| is set.
   void CreateAuthenticator(Authenticator::State preferred_initial_state,
                            const base::Closure& resume_callback);
 
@@ -90,6 +89,8 @@ class NegotiatingHostAuthenticator : public NegotiatingAuthenticatorBase {
   // Used only for pairing authenticators.
   scoped_refptr<PairingRegistry> pairing_registry_;
 
+  std::string client_id_;
+
   DISALLOW_COPY_AND_ASSIGN(NegotiatingHostAuthenticator);
 };