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

base/threading/watchdog_unittest.cc

Index: base/threading/watchdog_unittest.cc
diff --git a/base/threading/watchdog_unittest.cc b/base/threading/watchdog_unittest.cc
index b8cc7b7e004a392f3c533a3115b8c8c2593af34e..627f46d8a9bc55adc0d39745b80a05518bb6dd03 100644
--- a/base/threading/watchdog_unittest.cc
+++ b/base/threading/watchdog_unittest.cc
@@ -43,9 +43,7 @@ class WatchdogCounter : public Watchdog {
 
 class WatchdogTest : public testing::Test {
  public:
-  virtual void SetUp() override {
-    Watchdog::ResetStaticData();
-  }
+  void SetUp() override { Watchdog::ResetStaticData(); }
 };
 
 }  // namespace