Standardize usage of virtual/override/final specifiers in base/.

base/threading/sequenced_worker_pool_unittest.cc

Index: base/threading/sequenced_worker_pool_unittest.cc
diff --git a/base/threading/sequenced_worker_pool_unittest.cc b/base/threading/sequenced_worker_pool_unittest.cc
index b1fe2764442c9159c9614fe3abe102f6a496a67c..ed5f89694983ca707b977990a59982ca5a9fb83b 100644
--- a/base/threading/sequenced_worker_pool_unittest.cc
+++ b/base/threading/sequenced_worker_pool_unittest.cc
@@ -183,13 +183,7 @@ class SequencedWorkerPoolTest : public testing::Test {
     ResetPool();
   }
 
-  virtual ~SequencedWorkerPoolTest() {}
-
-  virtual void SetUp() override {}
-
-  virtual void TearDown() override {
-    pool()->Shutdown();
-  }
+  void TearDown() override { pool()->Shutdown(); }
 
   const scoped_refptr<SequencedWorkerPool>& pool() {
     return pool_owner_->pool();