Standardize usage of virtual/override/final specifiers.

chrome/utility/extensions/unpacker_unittest.cc

Index: chrome/utility/extensions/unpacker_unittest.cc
diff --git a/chrome/utility/extensions/unpacker_unittest.cc b/chrome/utility/extensions/unpacker_unittest.cc
index 99939f13658886af2c3b2eaa357a565608f77268..21e1bb6de8cb37c7fe6479a1483aa597ce3153fe 100644
--- a/chrome/utility/extensions/unpacker_unittest.cc
+++ b/chrome/utility/extensions/unpacker_unittest.cc
@@ -25,7 +25,7 @@ namespace keys = manifest_keys;
 
 class UnpackerTest : public testing::Test {
  public:
-  virtual ~UnpackerTest() {
+  ~UnpackerTest() override {
     LOG(WARNING) << "Deleting temp dir: "
                  << temp_dir_.path().LossyDisplayName();
     LOG(WARNING) << temp_dir_.Delete();