[Sync] Minor refactor around SyncCycle and ModelTypeSet usage.

components/sync/engine_impl/syncer_unittest.cc

 // Copyright 2012 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/sync/engine_impl/syncer.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <limits>
@@ skipping 220 matching lines @@
         FAIL() << "Handling unknown error type in unit tests!!";
     }
   }
 
   void OnActionableError(const SyncProtocolError& error) override {}
   void OnRetryTimeChanged(base::Time retry_time) override {}
   void OnThrottledTypesChanged(ModelTypeSet throttled_types) override {}
   void OnBackedOffTypesChanged(ModelTypeSet backed_off_types) override {}
   void OnMigrationRequested(ModelTypeSet types) override {}
 
-  void ResetCycle() { cycle_.reset(SyncCycle::Build(context_.get(), this)); }
+  void ResetCycle() {
+    cycle_ = base::MakeUnique<SyncCycle>(context_.get(), this);
+  }
 
   bool SyncShareNudge() {
     ResetCycle();
 
     // Pretend we've seen a local change, to make the nudge_tracker look normal.
     nudge_tracker_.RecordLocalChange(ModelTypeSet(BOOKMARKS));
 
     return syncer_->NormalSyncShare(context_->GetEnabledTypes(),
                                     &nudge_tracker_, cycle_.get());
   }
@@ skipping 5655 matching lines @@
     EXPECT_EQ("xyz", final_monitor_records["xyz"].extension_id);
     EXPECT_EQ(2049U, final_monitor_records["ABC"].bookmark_write_count);
     EXPECT_EQ(4U, final_monitor_records["xyz"].bookmark_write_count);
   } else {
     EXPECT_TRUE(final_monitor_records.empty())
         << "Should not restore records after successful bookmark commit.";
   }
 }
 
 }  // namespace syncer