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

sql/transaction_unittest.cc

Index: sql/transaction_unittest.cc
diff --git a/sql/transaction_unittest.cc b/sql/transaction_unittest.cc
index 5625041eb5fe34d2fc7447bbe7257e37cffc8b97..83d41259b2400380e98587266dc80a26eb1a8c94 100644
--- a/sql/transaction_unittest.cc
+++ b/sql/transaction_unittest.cc
@@ -12,7 +12,7 @@
 
 class SQLTransactionTest : public testing::Test {
  public:
-  virtual void SetUp() {
+  void SetUp() override {
     ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
     ASSERT_TRUE(db_.Open(
         temp_dir_.path().AppendASCII("SQLTransactionTest.db")));
@@ -20,9 +20,7 @@ class SQLTransactionTest : public testing::Test {
     ASSERT_TRUE(db().Execute("CREATE TABLE foo (a, b)"));
   }
 
-  virtual void TearDown() {
-    db_.Close();
-  }
+  void TearDown() override { db_.Close(); }
 
   sql::Connection& db() { return db_; }