[Sync] Replace manual DI with SetTestingFactory.

components/ukm/observers/sync_disable_observer_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/ukm/observers/sync_disable_observer.h"
 
 #include "base/observer_list.h"
 #include "components/sync/driver/fake_sync_service.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 10 matching lines @@
     initialized_ = true;
     has_passphrase_ = has_passphrase;
     preferred_data_types_ =
         enabled ? syncer::ModelTypeSet(syncer::HISTORY_DELETE_DIRECTIVES)
                 : syncer::ModelTypeSet();
     for (auto& observer : observers_) {
       observer.OnStateChanged(this);
     }
   }
 
-  void Shutdown() {
+  void Shutdown() override {
     for (auto& observer : observers_) {
       observer.OnSyncShutdown(this);
     }
   }
 
  private:
   // syncer::FakeSyncService:
   void AddObserver(syncer::SyncServiceObserver* observer) override {
     observers_.AddObserver(observer);
   }
@@ skipping 165 matching lines @@
   EXPECT_FALSE(observer.IsHistorySyncEnabledOnAllProfiles());
   EXPECT_TRUE(observer.ResetNotified());
   EXPECT_TRUE(observer.ResetPurged());
   sync.Shutdown();
   EXPECT_FALSE(observer.IsHistorySyncEnabledOnAllProfiles());
   EXPECT_FALSE(observer.ResetNotified());
   EXPECT_FALSE(observer.ResetPurged());
 }
 
 }  // namespace ukm