Provide correct guard for GCM connection tracking of login failures.

google_apis/gcm/engine/connection_event_tracker.cc

 // Copyright 2016 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 "google_apis/gcm/engine/connection_event_tracker.h"
 
 #include "base/time/time.h"
 #include "net/base/network_change_notifier.h"
 
 namespace {
@@ skipping 44 matching lines @@
 
   // A completed connection means that the old client event data has now been
   // sent to GCM. Delete old data.
   completed_events_.clear();
   number_discarded_events_ = 0;
 }
 
 void ConnectionEventTracker::ConnectionLoginFailed() {
   // A login failure would have originally been marked as a successful
   // connection, so now that it failed, that needs to be updated.
-  // TODO(harkness): Add back DCHECK which was removed. See
-  // https://crbug.com/673706.
+  DCHECK_EQ(current_event_.type(),
+            mcs_proto::ClientEvent::SUCCESSFUL_CONNECTION);
 
   current_event_.set_type(mcs_proto::ClientEvent::FAILED_CONNECTION);
   current_event_.clear_time_connection_established_ms();
   current_event_.set_error_code(net::ERR_CONNECTION_RESET);
 }
 
 void ConnectionEventTracker::ConnectionAttemptFailed(int error) {
   DCHECK_NE(error, net::OK);
 
   current_event_.set_type(mcs_proto::ClientEvent::FAILED_CONNECTION);
   current_event_.set_error_code(error);
 }
 
 void ConnectionEventTracker::WriteToLoginRequest(
     mcs_proto::LoginRequest* request) {
   DCHECK(request);
 
   // Add an event to represented the discarded events if needed.
   if (number_discarded_events_ > 0) {
     mcs_proto::ClientEvent* event = request->add_client_event();
     event->set_type(mcs_proto::ClientEvent::DISCARDED_EVENTS);
     event->set_number_discarded_events(number_discarded_events_);
   }
 
   for (const mcs_proto::ClientEvent& event : completed_events_)
     request->add_client_event()->CopyFrom(event);
 }
 
 }  // namespace gcm