components/precache/content/precache_manager_unittest.cc

// Copyright 2013 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/precache/content/precache_manager.h"

#include <stddef.h>

#include <map>
#include <memory>
#include <set>
#include <string>

#include "base/bind.h"
#include "base/callback.h"
#include "base/command_line.h"
#include "base/compiler_specific.h"
#include "base/files/file_path.h"
#include "base/files/scoped_temp_dir.h"
#include "base/location.h"
#include "base/run_loop.h"
#include "base/single_thread_task_runner.h"
#include "base/test/histogram_tester.h"
#include "base/threading/thread_task_runner_handle.h"
#include "components/history/core/browser/history_constants.h"
#include "components/history/core/browser/history_service.h"
#include "components/history/core/browser/history_types.h"
#include "components/precache/core/precache_database.h"
#include "components/precache/core/precache_switches.h"
#include "components/precache/core/proto/unfinished_work.pb.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/test/test_browser_context.h"
#include "content/public/test/test_browser_thread_bundle.h"
#include "net/http/http_response_headers.h"
#include "net/http/http_response_info.h"
#include "net/http/http_status_code.h"
#include "net/url_request/test_url_fetcher_factory.h"
#include "net/url_request/url_request_status.h"
#include "net/url_request/url_request_test_util.h"
#include "testing/gmock/include/gmock/gmock.h"
#include "testing/gtest/include/gtest/gtest.h"
#include "url/gurl.h"

namespace precache {

namespace {

using ::testing::_;
using ::testing::ContainerEq;
using ::testing::UnorderedElementsAre;
using ::testing::Invoke;
using ::testing::IsEmpty;
using ::testing::Pair;
using ::testing::SaveArg;

const char kConfigURL[] = "http://config-url.com";
const char kManifestURLPrefix[] = "http://manifest-url-prefix.com/";
const char kGoodManifestURL[] =
    "http://manifest-url-prefix.com/good-manifest.com";
const char kEvilManifestURL[] =
    "http://manifest-url-prefix.com/evil-manifest.com";

class TestURLFetcherCallback {
 public:
  std::unique_ptr<net::FakeURLFetcher> CreateURLFetcher(
      const GURL& url,
      net::URLFetcherDelegate* delegate,
      const std::string& response_data,
      net::HttpStatusCode response_code,
      net::URLRequestStatus::Status status) {
    std::unique_ptr<net::FakeURLFetcher> fetcher(new net::FakeURLFetcher(
        url, delegate, response_data, response_code, status));

    requested_urls_.insert(url);
    return fetcher;
  }

  const std::multiset<GURL>& requested_urls() const {
    return requested_urls_;
  }

 private:
  // Multiset with one entry for each URL requested.
  std::multiset<GURL> requested_urls_;
};

class MockHistoryService : public history::HistoryService {
 public:
  MockHistoryService() {
    ON_CALL(*this, HostRankIfAvailable(_, _))
        .WillByDefault(Invoke(
            [](const GURL& url, const base::Callback<void(int)>& callback) {
              callback.Run(history::kMaxTopHosts);
            }));
  }

  MOCK_CONST_METHOD2(TopHosts,
                     void(size_t num_hosts, const TopHostsCallback& callback));

  MOCK_CONST_METHOD2(HostRankIfAvailable,
                     void(const GURL& url,
                          const base::Callback<void(int)>& callback));
};

ACTION_P(ReturnHosts, starting_hosts) {
  arg1.Run(starting_hosts);
}

class TestPrecacheCompletionCallback {
 public:
  TestPrecacheCompletionCallback() : was_on_done_called_(false) {}

  void OnDone(bool precaching_started) { was_on_done_called_ = true; }

  PrecacheManager::PrecacheCompletionCallback GetCallback() {
    return base::Bind(&TestPrecacheCompletionCallback::OnDone,
                      base::Unretained(this));
  }

  bool was_on_done_called() const {
    return was_on_done_called_;
  }

 private:
  bool was_on_done_called_;
};

class PrecacheManagerUnderTest : public PrecacheManager {
 public:
  PrecacheManagerUnderTest(content::BrowserContext* browser_context,
                           const syncer::SyncService* const sync_service,
                           const history::HistoryService* const history_service,
                           const base::FilePath& db_path,
                           std::unique_ptr<PrecacheDatabase> precache_database)
      : PrecacheManager(browser_context,
                        sync_service,
                        history_service,
                        db_path,
                        std::move(precache_database)),
        control_group_(false) {}
  bool IsInExperimentGroup() const override { return !control_group_; }
  bool IsInControlGroup() const override { return control_group_; }
  bool IsPrecachingAllowed() const override { return true; }
  void SetInControlGroup(bool in_control_group) {
    control_group_ = in_control_group;
  }

 private:
  bool control_group_;
};

}  // namespace

class PrecacheManagerTest : public testing::Test {
 public:
  PrecacheManagerTest()
      : factory_(nullptr,
                 base::Bind(&TestURLFetcherCallback::CreateURLFetcher,
                            base::Unretained(&url_callback_))) {}

  ~PrecacheManagerTest() {
    // precache_manager_'s constructor releases a PrecacheDatabase and deletes
    // it on the DB thread. PrecacheDatabase already has a pending Init call
    // which will assert in debug builds because the directory passed to it is
    // deleted. So manually ensure that the task is run before browser_context_
    // is destructed.
    base::RunLoop().RunUntilIdle();
  }

 protected:
  void SetUp() override {
    base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
        switches::kPrecacheConfigSettingsURL, kConfigURL);
    base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
        switches::kPrecacheManifestURLPrefix, kManifestURLPrefix);
    std::unique_ptr<PrecacheDatabase> precache_database(
        new PrecacheDatabase());
    precache_database_ = precache_database.get();

    ASSERT_TRUE(scoped_temp_dir_.CreateUniqueTempDir());
    base::FilePath db_path = scoped_temp_dir_.GetPath().Append(
        base::FilePath(FILE_PATH_LITERAL("precache_database")));

    // Make the fetch of the precache configuration settings fail. Precaching
    // should still complete normally in this case.
    factory_.SetFakeResponse(GURL(kConfigURL), "",
                             net::HTTP_INTERNAL_SERVER_ERROR,
                             net::URLRequestStatus::FAILED);
    precache_manager_.reset(
        new PrecacheManagerUnderTest(
            &browser_context_, nullptr /* sync_service */,
            &history_service_, db_path, std::move(precache_database)));
    base::RunLoop().RunUntilIdle();

    info_.headers = new net::HttpResponseHeaders("");
  }

  void RecordStatsForPrecacheFetch(const GURL& url,
                                   const std::string& referrer_host,
                                   const base::TimeDelta& latency,
                                   const base::Time& fetch_time,
                                   const net::HttpResponseInfo& info,
                                   int64_t size) {
    precache_manager_->RecordStatsForFetch(url, GURL(referrer_host), latency,
                                           fetch_time, info, size);
    precache_database_->RecordURLPrefetch(url, referrer_host, fetch_time,
                                          info.was_cached, size);
  }

  // Must be declared first so that it is destroyed last.
  content::TestBrowserThreadBundle test_browser_thread_bundle_;
  base::ScopedTempDir scoped_temp_dir_;
  PrecacheDatabase* precache_database_;
  content::TestBrowserContext browser_context_;
  std::unique_ptr<PrecacheManagerUnderTest> precache_manager_;
  TestURLFetcherCallback url_callback_;
  net::FakeURLFetcherFactory factory_;
  TestPrecacheCompletionCallback precache_callback_;
  testing::NiceMock<MockHistoryService> history_service_;
  base::HistogramTester histograms_;
  net::HttpResponseInfo info_;
};

TEST_F(PrecacheManagerTest, StartAndFinishPrecaching) {
  EXPECT_FALSE(precache_manager_->IsPrecaching());

  MockHistoryService::TopHostsCallback top_hosts_callback;
  EXPECT_CALL(history_service_, TopHosts(NumTopHosts(), _))
      .WillOnce(SaveArg<1>(&top_hosts_callback));

  factory_.SetFakeResponse(GURL(kConfigURL), "", net::HTTP_OK,
                           net::URLRequestStatus::SUCCESS);
  factory_.SetFakeResponse(GURL(kGoodManifestURL), "", net::HTTP_OK,
                           net::URLRequestStatus::SUCCESS);

  precache_manager_->StartPrecaching(precache_callback_.GetCallback());
  base::RunLoop().RunUntilIdle();
  EXPECT_TRUE(precache_manager_->IsPrecaching());

  top_hosts_callback.Run(
      history::TopHostsList(1, std::make_pair("good-manifest.com", 1)));
  base::RunLoop().RunUntilIdle();  // For PrecacheFetcher.
  EXPECT_FALSE(precache_manager_->IsPrecaching());
  EXPECT_TRUE(precache_callback_.was_on_done_called());

  std::multiset<GURL> expected_requested_urls;
  expected_requested_urls.insert(GURL(kConfigURL));
  expected_requested_urls.insert(GURL(kGoodManifestURL));
  EXPECT_EQ(expected_requested_urls, url_callback_.requested_urls());
}

TEST_F(PrecacheManagerTest, StartAndFinishPrecachingWithUnfinishedHosts) {
  std::unique_ptr<PrecacheUnfinishedWork> unfinished_work(
      new PrecacheUnfinishedWork());
  unfinished_work->add_top_host()->set_hostname("evil-manifest.com");
  unfinished_work->set_start_time(base::Time::Now().ToInternalValue());
  precache_database_->SaveUnfinishedWork(std::move(unfinished_work));

  EXPECT_FALSE(precache_manager_->IsPrecaching());

  factory_.SetFakeResponse(GURL(kConfigURL), "", net::HTTP_OK,
                           net::URLRequestStatus::SUCCESS);
  factory_.SetFakeResponse(
      GURL(kEvilManifestURL), "",
      net::HTTP_OK, net::URLRequestStatus::SUCCESS);

  ASSERT_TRUE(precache_database_->GetLastPrecacheTimestamp().is_null());

  precache_manager_->StartPrecaching(precache_callback_.GetCallback());
  EXPECT_TRUE(precache_manager_->IsPrecaching());

  base::RunLoop().RunUntilIdle();  // For PrecacheFetcher.
  EXPECT_FALSE(precache_manager_->IsPrecaching());
  EXPECT_TRUE(precache_callback_.was_on_done_called());

  // The LastPrecacheTimestamp has been set.
  EXPECT_FALSE(precache_database_->GetLastPrecacheTimestamp().is_null());

  std::multiset<GURL> expected_requested_urls;
  expected_requested_urls.insert(GURL(kConfigURL));
  expected_requested_urls.insert(GURL(kEvilManifestURL));
  EXPECT_EQ(expected_requested_urls, url_callback_.requested_urls());
}

TEST_F(PrecacheManagerTest,
       StartAndCancelPrecachingBeforeUnfinishedWorkRetrieved) {
  EXPECT_FALSE(precache_manager_->IsPrecaching());

  precache_manager_->StartPrecaching(precache_callback_.GetCallback());
  EXPECT_TRUE(precache_manager_->IsPrecaching());
  precache_manager_->CancelPrecaching();
  EXPECT_FALSE(precache_manager_->IsPrecaching());

  base::RunLoop().RunUntilIdle();
  EXPECT_FALSE(precache_callback_.was_on_done_called());
}

TEST_F(PrecacheManagerTest, StartAndCancelPrecachingBeforeTopHostsCompleted) {
  EXPECT_FALSE(precache_manager_->IsPrecaching());

  MockHistoryService::TopHostsCallback top_hosts_callback;
  EXPECT_CALL(history_service_, TopHosts(NumTopHosts(), _))
      .WillOnce(SaveArg<1>(&top_hosts_callback));

  precache_manager_->StartPrecaching(precache_callback_.GetCallback());
  EXPECT_TRUE(precache_manager_->IsPrecaching());

  precache_manager_->CancelPrecaching();
  EXPECT_FALSE(precache_manager_->IsPrecaching());
  base::RunLoop().RunUntilIdle();

  top_hosts_callback.Run(
      history::TopHostsList(1, std::make_pair("starting-url.com", 1)));
  base::RunLoop().RunUntilIdle();
  EXPECT_FALSE(precache_manager_->IsPrecaching());
  EXPECT_FALSE(precache_callback_.was_on_done_called());
}

TEST_F(PrecacheManagerTest, StartAndCancelPrecachingBeforeURLsReceived) {
  EXPECT_FALSE(precache_manager_->IsPrecaching());

  MockHistoryService::TopHostsCallback top_hosts_callback;
  EXPECT_CALL(history_service_, TopHosts(NumTopHosts(), _))
      .WillOnce(SaveArg<1>(&top_hosts_callback));

  precache_manager_->StartPrecaching(precache_callback_.GetCallback());
  EXPECT_TRUE(precache_manager_->IsPrecaching());

  precache_manager_->CancelPrecaching();
  base::RunLoop().RunUntilIdle();
  EXPECT_FALSE(precache_manager_->IsPrecaching());
  top_hosts_callback.Run(
      history::TopHostsList(1, std::make_pair("starting-url.com", 1)));
  base::RunLoop().RunUntilIdle();  // For PrecacheFetcher.
  EXPECT_FALSE(precache_manager_->IsPrecaching());
  EXPECT_FALSE(precache_callback_.was_on_done_called());
  EXPECT_TRUE(url_callback_.requested_urls().empty());
}

TEST_F(PrecacheManagerTest, StartAndCancelPrecachingAfterURLsReceived) {
  EXPECT_FALSE(precache_manager_->IsPrecaching());

  PrecacheManifest good_manifest;
  good_manifest.add_resource()->set_url("http://good-resource.com");

  EXPECT_CALL(history_service_, TopHosts(NumTopHosts(), _))
      .WillOnce(ReturnHosts(
          history::TopHostsList(1, std::make_pair("starting-url.com", 1))));

  precache_manager_->StartPrecaching(precache_callback_.GetCallback());

  EXPECT_TRUE(precache_manager_->IsPrecaching());
  // Run a task to get unfinished work, and to get hosts.
  for (int i = 0; i < 2; ++i) {
    base::RunLoop run_loop;
    base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
                                                  run_loop.QuitClosure());
    run_loop.Run();
  }
  // base::RunLoop().RunUntilIdle();
  precache_manager_->CancelPrecaching();
  EXPECT_FALSE(precache_manager_->IsPrecaching());

  base::RunLoop().RunUntilIdle();  // For PrecacheFetcher.
  EXPECT_FALSE(precache_manager_->IsPrecaching());
  EXPECT_FALSE(precache_callback_.was_on_done_called());

  std::multiset<GURL> expected_requested_urls;
  expected_requested_urls.insert(GURL(kConfigURL));
  EXPECT_EQ(expected_requested_urls, url_callback_.requested_urls());
}

// TODO(rajendrant): Add unittests for
// PrecacheUtil::UpdatePrecacheMetricsAndState() for more test coverage.
TEST_F(PrecacheManagerTest, RecordStatsForFetchWithSizeZero) {
  // Fetches with size 0 should be ignored.
  precache_manager_->RecordStatsForFetch(GURL("http://url.com"), GURL(),
                                         base::TimeDelta(), base::Time(), info_,
                                         0);
  base::RunLoop().RunUntilIdle();
  EXPECT_THAT(histograms_.GetTotalCountsForPrefix("Precache."), IsEmpty());
}

TEST_F(PrecacheManagerTest, RecordStatsForFetchWithNonHTTP) {
  // Fetches for URLs with schemes other than HTTP or HTTPS should be ignored.
  precache_manager_->RecordStatsForFetch(GURL("ftp://ftp.com"), GURL(),
                                         base::TimeDelta(), base::Time(), info_,
                                         1000);
  base::RunLoop().RunUntilIdle();
  EXPECT_THAT(histograms_.GetTotalCountsForPrefix("Precache."), IsEmpty());
}

TEST_F(PrecacheManagerTest, RecordStatsForFetchWithEmptyURL) {
  // Fetches for empty URLs should be ignored.
  precache_manager_->RecordStatsForFetch(GURL(), GURL(), base::TimeDelta(),
                                         base::Time(), info_, 1000);
  base::RunLoop().RunUntilIdle();
  EXPECT_THAT(histograms_.GetTotalCountsForPrefix("Precache."), IsEmpty());
}

TEST_F(PrecacheManagerTest, RecordStatsForFetchDuringPrecaching) {
  EXPECT_CALL(history_service_, TopHosts(NumTopHosts(), _))
      .WillOnce(ReturnHosts(history::TopHostsList()));

  precache_manager_->StartPrecaching(precache_callback_.GetCallback());

  EXPECT_TRUE(precache_manager_->IsPrecaching());
  RecordStatsForPrecacheFetch(GURL("http://url.com"), std::string(),
                              base::TimeDelta(), base::Time(), info_, 1000);
  base::RunLoop().RunUntilIdle();
  precache_manager_->CancelPrecaching();

  // For PrecacheFetcher and RecordURLPrecached.
  base::RunLoop().RunUntilIdle();
  EXPECT_THAT(
      histograms_.GetTotalCountsForPrefix("Precache."),
      UnorderedElementsAre(Pair("Precache.DownloadedPrecacheMotivated", 1),
                           Pair("Precache.Fetch.PercentCompleted", 1),
                           Pair("Precache.Fetch.ResponseBytes.Network", 1),
                           Pair("Precache.Fetch.ResponseBytes.Total", 1),
                           Pair("Precache.Fetch.TimeToComplete", 1),
                           Pair("Precache.Latency.Prefetch", 1),
                           Pair("Precache.Freshness.Prefetch", 1)));
}

TEST_F(PrecacheManagerTest, RecordStatsForFetchHTTP) {
  precache_manager_->RecordStatsForFetch(GURL("http://http-url.com"), GURL(),
                                         base::TimeDelta(), base::Time(), info_,
                                         1000);
  base::RunLoop().RunUntilIdle();

  EXPECT_THAT(histograms_.GetTotalCountsForPrefix("Precache."),
              UnorderedElementsAre(
                  Pair("Precache.DownloadedNonPrecache", 1),
                  Pair("Precache.CacheStatus.NonPrefetch", 1),
                  Pair("Precache.Latency.NonPrefetch", 1),
                  Pair("Precache.Latency.NonPrefetch.NonTopHosts", 1)));
}

TEST_F(PrecacheManagerTest, RecordStatsForFetchHTTPS) {
  precache_manager_->RecordStatsForFetch(GURL("https://https-url.com"), GURL(),
                                         base::TimeDelta(), base::Time(), info_,
                                         1000);
  base::RunLoop().RunUntilIdle();

  EXPECT_THAT(histograms_.GetTotalCountsForPrefix("Precache."),
              UnorderedElementsAre(
                  Pair("Precache.DownloadedNonPrecache", 1),
                  Pair("Precache.CacheStatus.NonPrefetch", 1),
                  Pair("Precache.Latency.NonPrefetch", 1),
                  Pair("Precache.Latency.NonPrefetch.NonTopHosts", 1)));
}

TEST_F(PrecacheManagerTest, RecordStatsForFetchInTopHosts) {
  EXPECT_CALL(history_service_,
              HostRankIfAvailable(GURL("http://referrer.com"), _))
      .WillOnce(Invoke(
          [](const GURL& url, const base::Callback<void(int)>& callback) {
            callback.Run(0);
          }));
  precache_manager_->RecordStatsForFetch(
      GURL("http://http-url.com"), GURL("http://referrer.com"),
      base::TimeDelta(), base::Time(), info_, 1000);
  base::RunLoop().RunUntilIdle();

  EXPECT_THAT(
      histograms_.GetTotalCountsForPrefix("Precache."),
      UnorderedElementsAre(Pair("Precache.DownloadedNonPrecache", 1),
                           Pair("Precache.CacheStatus.NonPrefetch", 1),
                           Pair("Precache.Latency.NonPrefetch", 1),
                           Pair("Precache.Latency.NonPrefetch.TopHosts", 1)));
}

TEST_F(PrecacheManagerTest, DeleteExpiredPrecacheHistory) {
  // TODO(twifkak): Split this into multiple tests.
  base::HistogramTester::CountsMap expected_histogram_count_map;

  // This test has to use Time::Now() because StartPrecaching uses Time::Now().
  const base::Time kCurrentTime = base::Time::Now();
  EXPECT_CALL(history_service_, TopHosts(NumTopHosts(), _))
      .Times(2)
      .WillRepeatedly(ReturnHosts(history::TopHostsList()));

  precache_manager_->StartPrecaching(precache_callback_.GetCallback());
  EXPECT_TRUE(precache_manager_->IsPrecaching());

  // Precache a bunch of URLs, with different fetch times.
  RecordStatsForPrecacheFetch(
      GURL("http://old-fetch.com"), std::string(), base::TimeDelta(),
      kCurrentTime - base::TimeDelta::FromDays(61), info_, 1000);
  RecordStatsForPrecacheFetch(
      GURL("http://recent-fetch.com"), std::string(), base::TimeDelta(),
      kCurrentTime - base::TimeDelta::FromDays(59), info_, 1000);
  RecordStatsForPrecacheFetch(
      GURL("http://yesterday-fetch.com"), std::string(), base::TimeDelta(),
      kCurrentTime - base::TimeDelta::FromDays(1), info_, 1000);
  expected_histogram_count_map["Precache.DownloadedPrecacheMotivated"] += 3;
  expected_histogram_count_map["Precache.Fetch.PercentCompleted"]++;
  expected_histogram_count_map["Precache.Fetch.ResponseBytes.Network"]++;
  expected_histogram_count_map["Precache.Fetch.ResponseBytes.Total"]++;
  expected_histogram_count_map["Precache.Fetch.TimeToComplete"]++;
  expected_histogram_count_map["Precache.Latency.Prefetch"] += 3;
  expected_histogram_count_map["Precache.Freshness.Prefetch"] += 3;
  base::RunLoop().RunUntilIdle();

  precache_manager_->CancelPrecaching();
  base::RunLoop().RunUntilIdle();

  // Disable pause-resume.
  precache_database_->DeleteUnfinishedWork();
  base::RunLoop().RunUntilIdle();

  // For PrecacheFetcher and RecordURLPrecached.
  base::RunLoop().RunUntilIdle();
  EXPECT_THAT(histograms_.GetTotalCountsForPrefix("Precache."),
              ContainerEq(expected_histogram_count_map));

  // The expired precache will be deleted during precaching this time.
  precache_manager_->StartPrecaching(precache_callback_.GetCallback());
  EXPECT_TRUE(precache_manager_->IsPrecaching());
  base::RunLoop().RunUntilIdle();

  // The precache fetcher runs until done, which records these histograms,
  // and then cancels precaching, which records these histograms again.
  // In practice
  expected_histogram_count_map["Precache.Fetch.PercentCompleted"]++;
  expected_histogram_count_map["Precache.Fetch.ResponseBytes.Network"]++;
  expected_histogram_count_map["Precache.Fetch.ResponseBytes.Total"]++;
  // For PrecacheFetcher and RecordURLPrecached.
  base::RunLoop().RunUntilIdle();
  EXPECT_FALSE(precache_manager_->IsPrecaching());

  // A fetch for the same URL as the expired precache was served from the cache,
  // but it isn't reported as saved bytes because it had expired in the precache
  // history.
  info_.was_cached = true;  // From now on all fetches are cached.
  precache_manager_->RecordStatsForFetch(GURL("http://old-fetch.com"), GURL(),
                                         base::TimeDelta(), kCurrentTime, info_,
                                         1000);
  expected_histogram_count_map["Precache.Fetch.TimeToComplete"]++;
  expected_histogram_count_map["Precache.CacheStatus.NonPrefetch"]++;
  expected_histogram_count_map["Precache.Latency.NonPrefetch"]++;
  expected_histogram_count_map["Precache.Latency.NonPrefetch.NonTopHosts"]++;
  expected_histogram_count_map["Precache.TimeSinceLastPrecache"] += 1;

  base::RunLoop().RunUntilIdle();
  EXPECT_THAT(histograms_.GetTotalCountsForPrefix("Precache."),
              ContainerEq(expected_histogram_count_map));

  // The other precaches should not have expired, so the following fetches from
  // the cache should count as saved bytes.
  precache_manager_->RecordStatsForFetch(GURL("http://recent-fetch.com"),
                                         GURL(), base::TimeDelta(),
                                         kCurrentTime, info_, 1000);
  precache_manager_->RecordStatsForFetch(GURL("http://yesterday-fetch.com"),
                                         GURL(), base::TimeDelta(),
                                         kCurrentTime, info_, 1000);
  expected_histogram_count_map["Precache.CacheStatus.NonPrefetch"] += 2;
  expected_histogram_count_map
      ["Precache.CacheStatus.NonPrefetch.FromPrecache"] += 2;
  expected_histogram_count_map["Precache.Latency.NonPrefetch"] += 2;
  expected_histogram_count_map["Precache.Latency.NonPrefetch.NonTopHosts"] += 2;
  expected_histogram_count_map["Precache.Saved"] += 2;
  expected_histogram_count_map["Precache.TimeSinceLastPrecache"] += 2;
  expected_histogram_count_map["Precache.Saved.Freshness"] = 2;

  base::RunLoop().RunUntilIdle();
  EXPECT_THAT(histograms_.GetTotalCountsForPrefix("Precache."),
              ContainerEq(expected_histogram_count_map));
}

}  // namespace precache