Update ConnectionEventTracker to check if there is an in progress attempt.

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 {
 
 // The maxiumum number of events which are stored before deleting old ones.
 // This mirrors the behaviour of the GMS Core connection tracking.
 constexpr size_t kMaxClientEvents = 30;
 
 }  // namespace
 
 namespace gcm {
 
 ConnectionEventTracker::ConnectionEventTracker() = default;
 
 ConnectionEventTracker::~ConnectionEventTracker() = default;
 
+bool ConnectionEventTracker::EventInProgress() {
+  return current_event_.has_time_connection_started_ms();
+}
+
 void ConnectionEventTracker::StartConnectionAttempt() {
   // TODO(harkness): Can we dcheck here that there is not an in progress
   // connection?
   current_event_.set_time_connection_started_ms(base::Time::Now().ToJavaTime());
   // The connection type is passed to the server and stored there, so the
   // values should remain consistent.
   current_event_.set_network_type(
       static_cast<int>(net::NetworkChangeNotifier::GetConnectionType()));
 }
 
 void ConnectionEventTracker::EndConnectionAttempt() {
-  // TODO(harkness): Modify tests so that we can put a DCHECK here.
+  // EndConnectionAttempt should only be called if there was a previous
+  // StartConnectionAttempt.

[Peter Beverloo, 2017/01/12 16:03:27]

optional nit: I'd drop the comment - that's obvious from the DCHECK

[harkness, 2017/01/16 12:20:37]

Done.

+  DCHECK(EventInProgress());
+
   if (completed_events_.size() == kMaxClientEvents) {
     // Don't let the completed events grow beyond the max.
     completed_events_.pop_front();
     number_discarded_events_++;
   }
 
-  // Current event is now completed, so add it to our list of completed events.
+  // Current event is finished, so add it to our list of completed events.
   current_event_.set_time_connection_ended_ms(base::Time::Now().ToJavaTime());
   completed_events_.push_back(current_event_);
   current_event_.Clear();
 }
 
 void ConnectionEventTracker::ConnectionAttemptSucceeded() {
   // Record the successful connection so information about it can be sent in the
   // next login request. If there is a login failure, this will need to be
   // updated to a failed connection.
   current_event_.set_type(mcs_proto::ClientEvent::SUCCESSFUL_CONNECTION);
@@ skipping 33 matching lines @@
     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