[Remote suggestions] Remove the unique_ptr wrapper around callbacks

components/ntp_snippets/remote/remote_suggestions_provider_impl_unittest.cc

 // Copyright 2015 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/ntp_snippets/remote/remote_suggestions_provider_impl.h"
 
 #include <memory>
 #include <utility>
 #include <vector>
 
@@ skipping 539 matching lines @@
   void SetUpHttpError() {
     fake_url_fetcher_factory_.SetFakeResponse(test_url_, /*json=*/std::string(),
                                               net::HTTP_NOT_FOUND,
                                               net::URLRequestStatus::SUCCESS);
   }
 
   void LoadFromJSONString(RemoteSuggestionsProviderImpl* service,
                           const std::string& json) {
     SetUpFetchResponse(json);
     service->FetchSuggestions(/*interactive_request=*/true,
-                              /*callback=*/nullptr);
+                              RemoteSuggestionsProvider::FetchStatusCallback());
     base::RunLoop().RunUntilIdle();
   }
 
   void LoadMoreFromJSONString(RemoteSuggestionsProviderImpl* service,
                               const Category& category,
                               const std::string& json,
                               const std::set<std::string>& known_ids,
                               FetchDoneCallback callback) {
     SetUpFetchResponse(json);
     EXPECT_CALL(*scheduler(), AcquireQuotaForInteractiveFetch())
@@ skipping 1153 matching lines @@
   WaitForSuggestionsProviderInitialization(service.get(),
                                            /*set_empty_response=*/true);
   EXPECT_EQ(
       simple_test_clock_ptr->Now().ToInternalValue(),
       pref_service()->GetInt64(prefs::kLastSuccessfulBackgroundFetchTime));
 
   // Advance the time and check whether the time was updated correctly after the
   // background fetch.
   simple_test_clock_ptr->Advance(TimeDelta::FromHours(1));
 
-  service->RefetchInTheBackground(/*callback=*/nullptr);
+  service->RefetchInTheBackground(
+      RemoteSuggestionsProvider::FetchStatusCallback());
   base::RunLoop().RunUntilIdle();
   // TODO(jkrcal): Move together with the pref storage into the scheduler.
   EXPECT_EQ(
       simple_test_clock_ptr->Now().ToInternalValue(),
       pref_service()->GetInt64(prefs::kLastSuccessfulBackgroundFetchTime));
   // TODO(markusheintz): Add a test that simulates a browser restart once the
   // scheduler refactoring is done (crbug.com/672434).
 }
 
 TEST_F(RemoteSuggestionsProviderImplTest, CallsSchedulerWhenReady) {
@@ skipping 66 matching lines @@
   WaitForSuggestionsProviderInitialization(service.get(),
                                            /*set_empty_response=*/true);
 
   // The scheduler should be notified of clearing the history.
   EXPECT_CALL(*scheduler(), OnSuggestionsCleared());
   service->OnStatusChanged(RemoteSuggestionsStatus::ENABLED_AND_SIGNED_OUT,
                            RemoteSuggestionsStatus::ENABLED_AND_SIGNED_IN);
 }
 
 }  // namespace ntp_snippets