[Offline Pages] Add expiration in internal log.

components/offline_pages/offline_page_model_impl.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 "components/offline_pages/offline_page_model_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/bind.h"
@@ skipping 646 matching lines @@
 void OfflinePageModelImpl::OnExpirePageDone(int64_t offline_id,
                                             const base::Time& expiration_time,
                                             bool success) {
   UMA_HISTOGRAM_BOOLEAN("OfflinePages.ExpirePage.StoreUpdateResult", success);
   if (!success)
     return;
   const auto& iter = offline_pages_.find(offline_id);
   if (iter != offline_pages_.end()) {
     iter->second.expiration_time = expiration_time;
     ClientId client_id = iter->second.client_id;
+    offline_event_logger_.RecordPageExpired(std::to_string(offline_id));
     base::HistogramBase* histogram = base::Histogram::FactoryGet(
         AddHistogramSuffix(client_id, "OfflinePages.ExpirePage.PageLifetime"),
         1, base::TimeDelta::FromDays(30).InMinutes(), 50,
         base::HistogramBase::kUmaTargetedHistogramFlag);
     histogram->Add((expiration_time - iter->second.creation_time).InMinutes());
     histogram = base::Histogram::FactoryGet(
         AddHistogramSuffix(client_id,
                            "OfflinePages.ExpirePage.TimeSinceLastAccess"),
         1, base::TimeDelta::FromDays(30).InMinutes(), 50,
         base::HistogramBase::kUmaTargetedHistogramFlag);
@@ skipping 393 matching lines @@
 void OfflinePageModelImpl::RunWhenLoaded(const base::Closure& task) {
   if (!is_loaded_) {
     delayed_tasks_.push_back(task);
     return;
   }
 
   base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, task);
 }
 
 }  // namespace offline_pages