Standardize usage of virtual/override/final specifiers.

components/metrics/serialization/serialization_utils_unittest.cc

Index: components/metrics/serialization/serialization_utils_unittest.cc
diff --git a/components/metrics/serialization/serialization_utils_unittest.cc b/components/metrics/serialization/serialization_utils_unittest.cc
index aa1c7243113bc7e0a6e09cc92fa8b6cfbf52b68f..083735ccb5c4d5d65c3e5f38a412c4828d9b7eb2 100644
--- a/components/metrics/serialization/serialization_utils_unittest.cc
+++ b/components/metrics/serialization/serialization_utils_unittest.cc
@@ -25,9 +25,7 @@ class SerializationUtilsTest : public testing::Test {
     }
   }
 
-  virtual void SetUp() override {
-    base::DeleteFile(filepath, false);
-  }
+  void SetUp() override { base::DeleteFile(filepath, false); }
 
   void TestSerialization(MetricSample* sample) {
     std::string serialized(sample->ToString());