Standardize usage of virtual/override/final specifiers.

content/browser/startup_task_runner_unittest.cc

Index: content/browser/startup_task_runner_unittest.cc
diff --git a/content/browser/startup_task_runner_unittest.cc b/content/browser/startup_task_runner_unittest.cc
index d8b6224387ee882d645bf4c86e5c4bfada6bd931..2ecf9ca63c58c4c32e3f780f607d552e53768ab8 100644
--- a/content/browser/startup_task_runner_unittest.cc
+++ b/content/browser/startup_task_runner_unittest.cc
@@ -42,8 +42,7 @@ void Observer(int result) {
 
 class StartupTaskRunnerTest : public testing::Test {
  public:
-
-  virtual void SetUp() {
+  void SetUp() override {
     last_task_ = 0;
     observer_calls = 0;
     task_count = 0;