Add histograms and NetLog for host cache persistence

components/cronet/host_cache_persistence_manager_unittest.cc

 // Copyright 2017 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/cronet/host_cache_persistence_manager.h"
 
 #include "base/test/scoped_mock_time_message_loop_task_runner.h"
 #include "base/test/scoped_task_environment.h"
 #include "base/values.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/testing_pref_service.h"
 #include "net/base/net_errors.h"
 #include "net/dns/host_cache.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace cronet {
 
 class HostCachePersistenceManagerTest : public testing::Test {
  protected:
   void SetUp() override {
     cache_ = net::HostCache::CreateDefaultCache();
     pref_service_ = base::MakeUnique<TestingPrefServiceSimple>();
     pref_service_->registry()->RegisterListPref(kPrefName);
   }
 
   void MakePersistenceManager(base::TimeDelta delay) {
     persistence_manager_ = base::MakeUnique<HostCachePersistenceManager>(
-        cache_.get(), pref_service_.get(), kPrefName, delay);
+        cache_.get(), pref_service_.get(), kPrefName, delay, nullptr);
   }
 
   // Sets an entry in the HostCache in order to trigger a pref write. The
   // caller is responsible for making sure this is a change that will trigger
   // a write, and the HostCache's interaction with its PersistenceDelegate is
   // assumed to work (it's tested in net/dns/host_cache_unittest.cc).
   void WriteToCache(const std::string& host) {
     net::HostCache::Key key(host, net::ADDRESS_FAMILY_UNSPECIFIED, 0);
     net::HostCache::Entry entry(net::OK, net::AddressList());
     cache_->Set(key, entry, base::TimeTicks::Now(),
@@ skipping 134 matching lines @@
   MakePersistenceManager(base::TimeDelta::FromSeconds(1));
   ASSERT_EQ(0u, cache_->size());
 
   CheckPref(0);
   InitializePref();
   CheckPref(3);
   ASSERT_EQ(3u, cache_->size());
 }
 
 }  // namespace cronet