Standardize usage of virtual/override/final in sync/

sync/syncable/syncable_unittest.cc

Index: sync/syncable/syncable_unittest.cc
diff --git a/sync/syncable/syncable_unittest.cc b/sync/syncable/syncable_unittest.cc
index 7115aa4c22032c565fa46e92a51547de7ba6a9f2..5706106034a90727e4f7578d34bd209d38dae423 100644
--- a/sync/syncable/syncable_unittest.cc
+++ b/sync/syncable/syncable_unittest.cc
@@ -50,10 +50,9 @@ class TestBackingStore : public OnDiskDirectoryBackingStore {
   TestBackingStore(const std::string& dir_name,
                    const base::FilePath& backing_filepath);
 
-  virtual ~TestBackingStore();
+  ~TestBackingStore() override;
 
-  virtual bool SaveChanges(const Directory::SaveChangesSnapshot& snapshot)
-      override;
+  bool SaveChanges(const Directory::SaveChangesSnapshot& snapshot) override;
 
    void StartFailingSaveChanges() {
      fail_save_changes_ = true;
@@ -90,7 +89,7 @@ class TestDirectory : public Directory {
       const std::string& dir_name,
       const base::FilePath& backing_filepath);
 
-  virtual ~TestDirectory();
+  ~TestDirectory() override;
 
   void StartFailingSaveChanges() {
     backing_store_->StartFailingSaveChanges();