Add PendingEvents UMA to ConnectionEventTracker shutdown.

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/metrics/histogram_macros.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;
+ConnectionEventTracker::~ConnectionEventTracker() {
+  UMA_HISTOGRAM_ENUMERATION("GCM.PendingConnectionEventsAtShutdown",
+                            completed_events_.size(), kMaxClientEvents + 1);
+}
 
 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()));
 }
@@ skipping 53 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