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

base/files/file_util_unittest.cc

Index: base/files/file_util_unittest.cc
diff --git a/base/files/file_util_unittest.cc b/base/files/file_util_unittest.cc
index 29d51330dcdcd7378e1a8487c4c2dcafc7a57a7d..313ed036dc5ab23770e1bfcb70f88bc26ec48871 100644
--- a/base/files/file_util_unittest.cc
+++ b/base/files/file_util_unittest.cc
@@ -184,7 +184,7 @@ const int FILES_AND_DIRECTORIES =
 // to be a PlatformTest
 class FileUtilTest : public PlatformTest {
  protected:
-  virtual void SetUp() override {
+  void SetUp() override {
     PlatformTest::SetUp();
     ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
   }
@@ -2170,7 +2170,7 @@ TEST_F(FileUtilTest, IsDirectoryEmpty) {
 // with a common SetUp() method.
 class VerifyPathControlledByUserTest : public FileUtilTest {
  protected:
-  virtual void SetUp() override {
+  void SetUp() override {
     FileUtilTest::SetUp();
 
     // Create a basic structure used by each test.