Introduce flag to disable static popular sites.

components/ntp_tiles/popular_sites_impl_unittest.cc

Index: components/ntp_tiles/popular_sites_impl_unittest.cc
diff --git a/components/ntp_tiles/popular_sites_impl_unittest.cc b/components/ntp_tiles/popular_sites_impl_unittest.cc
index d5502037fde5e76a6121e43e380427a96b29514a..1deff6bd575927161c6b359c202d504d7595a3c4 100644
--- a/components/ntp_tiles/popular_sites_impl_unittest.cc
+++ b/components/ntp_tiles/popular_sites_impl_unittest.cc
@@ -18,9 +18,11 @@
 #include "base/memory/ptr_util.h"
 #include "base/optional.h"
 #include "base/run_loop.h"
+#include "base/test/scoped_feature_list.h"
 #include "base/test/sequenced_worker_pool_owner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/values.h"
+#include "components/ntp_tiles/constants.h"
 #include "components/ntp_tiles/json_unsafe_parser.h"
 #include "components/ntp_tiles/pref_names.h"
 #include "components/ntp_tiles/switches.h"
@@ -60,7 +62,7 @@ size_t GetNumberOfDefaultPopularSitesForPlatform() {
 #if defined(OS_ANDROID) || defined(OS_IOS)
   return 8ul;
 #else
-  return 0;
+  return 0ul;
 #endif
 }
 
@@ -83,18 +85,19 @@ class PopularSitesTest : public ::testing::Test {
             {kFaviconUrl, "https://www.chromium.org/favicon.ico"},
         },
         worker_pool_owner_(2, "PopularSitesTest."),
+        prefs_(new sync_preferences::TestingPrefServiceSyncable()),
         url_fetcher_factory_(nullptr) {
     base::CommandLine::ForCurrentProcess()->AppendSwitch(
         switches::kEnableNTPPopularSites);
-    PopularSitesImpl::RegisterProfilePrefs(prefs_.registry());
+    PopularSitesImpl::RegisterProfilePrefs(prefs_->registry());
     CHECK(scoped_cache_dir_.CreateUniqueTempDir());
     cache_dir_ = scoped_cache_dir_.GetPath();
   }
 
   void SetCountryAndVersion(const std::string& country,
                             const std::string& version) {
-    prefs_.SetString(prefs::kPopularSitesOverrideCountry, country);
-    prefs_.SetString(prefs::kPopularSitesOverrideVersion, version);
+    prefs_->SetString(prefs::kPopularSitesOverrideCountry, country);
+    prefs_->SetString(prefs::kPopularSitesOverrideVersion, version);
   }
 
   void RespondWithJSON(const std::string& url,
@@ -123,6 +126,11 @@ class PopularSitesTest : public ::testing::Test {
                                          net::URLRequestStatus::SUCCESS);
   }
 
+  void ReregisterProfilePrefs() {
+    prefs_ = base::MakeUnique<sync_preferences::TestingPrefServiceSyncable>();
+    PopularSitesImpl::RegisterProfilePrefs(prefs_->registry());
+  }
+
   // Returns an optional bool representing whether the completion callback was
   // called at all, and if yes which was the returned bool value.
   base::Optional<bool> FetchPopularSites(bool force_download,
@@ -152,7 +160,7 @@ class PopularSitesTest : public ::testing::Test {
   std::unique_ptr<PopularSites> CreatePopularSites(
       net::URLRequestContextGetter* context) {
     return base::MakeUnique<PopularSitesImpl>(
-        worker_pool_owner_.pool().get(), &prefs_,
+        worker_pool_owner_.pool().get(), prefs_.get(),
         /*template_url_service=*/nullptr,
         /*variations_service=*/nullptr, context, cache_dir_,
         base::Bind(JsonUnsafeParser::Parse));
@@ -166,7 +174,7 @@ class PopularSitesTest : public ::testing::Test {
   base::SequencedWorkerPoolOwner worker_pool_owner_;
   base::ScopedTempDir scoped_cache_dir_;
   base::FilePath cache_dir_;
-  sync_preferences::TestingPrefServiceSyncable prefs_;
+  std::unique_ptr<sync_preferences::TestingPrefServiceSyncable> prefs_;
   net::FakeURLFetcherFactory url_fetcher_factory_;
 };
 
@@ -180,7 +188,20 @@ TEST_F(PopularSitesTest, ContainsDefaultTilesRightAfterConstruction) {
               Eq(GetNumberOfDefaultPopularSitesForPlatform()));
 }
 
-TEST_F(PopularSitesTest, Zasic) {
+TEST_F(PopularSitesTest, IsEmptyOnConstructionIfDisabledByTrial) {
+  base::test::ScopedFeatureList override_features;
+  override_features.InitAndDisableFeature(kPopularSitesBakedInContentFeature);
+  ReregisterProfilePrefs();
+
+  scoped_refptr<net::TestURLRequestContextGetter> url_request_context(
+      new net::TestURLRequestContextGetter(
+          base::ThreadTaskRunnerHandle::Get()));
+  auto popular_sites = CreatePopularSites(url_request_context.get());
+
+  EXPECT_THAT(popular_sites->sites().size(), Eq(0ul));
+}
+
+TEST_F(PopularSitesTest, ShouldSucceedFetching) {
   SetCountryAndVersion("ZZ", "9");
   RespondWithJSON(
       "https://www.gstatic.com/chrome/ntp/suggested_sites_ZZ_9.json",