[Draft] Fix canceling pin prompt causes host overload

remoting/host/chromoting_host.cc

Index: remoting/host/chromoting_host.cc
diff --git a/remoting/host/chromoting_host.cc b/remoting/host/chromoting_host.cc
index e4bdae75990a3a93c2c1ac8229ee2ceb544ee95b..469c5b2849f824a9c2235a1fa705baddafe028b0 100644
--- a/remoting/host/chromoting_host.cc
+++ b/remoting/host/chromoting_host.cc
@@ -171,6 +171,20 @@ void ChromotingHost::SetMaximumSessionDuration(
 
 ////////////////////////////////////////////////////////////////////////////
 // protocol::ClientSession::EventHandler implementation.
+void ChromotingHost::OnSessionAuthenticating(ClientSession* client) {
+  // We treat each incoming connection as a failure to authenticate,
+  // and clear the backoff when a connection successfully
+  // authenticates. This allows the backoff to protect from parallel
+  // connection attempts as well as sequential ones.
+  if (login_backoff_.ShouldRejectRequest()) {
+    LOG(WARNING) << "Disconnecting client " << client->client_jid() << " due to"
+                    " an overload of failed login attempts.";
+    client->DisconnectSession();
+    return;
+  }
+  login_backoff_.InformOfRequest(false);
+}
+
 bool ChromotingHost::OnSessionAuthenticated(ClientSession* client) {
   DCHECK(CalledOnValidThread());
 
@@ -265,16 +279,12 @@ void ChromotingHost::OnIncomingSession(
   }
 
   if (login_backoff_.ShouldRejectRequest()) {
+    LOG(WARNING) << "Rejecting connection due to"
+                    " an overload of failed login attempts.";
     *response = protocol::SessionManager::OVERLOAD;
     return;
   }
 
-  // We treat each incoming connection as a failure to authenticate,
-  // and clear the backoff when a connection successfully
-  // authenticates. This allows the backoff to protect from parallel
-  // connection attempts as well as sequential ones.
-  login_backoff_.InformOfRequest(false);
-
   protocol::SessionConfig config;
   if (!protocol_config_->Select(session->candidate_config(), &config)) {
     LOG(WARNING) << "Rejecting connection from " << session->jid()