Standardize usage of virtual/override/final in chrome/browser/history

chrome/browser/history/expire_history_backend.cc

Index: chrome/browser/history/expire_history_backend.cc
diff --git a/chrome/browser/history/expire_history_backend.cc b/chrome/browser/history/expire_history_backend.cc
index b4791d9293a8b91ba7f95892ad74d222b4ef62fa..a7c952890eca2e6ca5aaea87d35fa63229c561fd 100644
--- a/chrome/browser/history/expire_history_backend.cc
+++ b/chrome/browser/history/expire_history_backend.cc
@@ -44,10 +44,10 @@ const int kEarlyExpirationAdvanceDays = 3;
 // time. This is the most general reader.
 class AllVisitsReader : public ExpiringVisitsReader {
  public:
-  virtual bool Read(base::Time end_time,
-                    HistoryDatabase* db,
-                    VisitVector* visits,
-                    int max_visits) const override {
+  bool Read(base::Time end_time,
+            HistoryDatabase* db,
+            VisitVector* visits,
+            int max_visits) const override {
     DCHECK(db) << "must have a database to operate upon";
     DCHECK(visits) << "visit vector has to exist in order to populate it";
 
@@ -66,10 +66,10 @@ class AllVisitsReader : public ExpiringVisitsReader {
 //   but not past the current time.
 class AutoSubframeVisitsReader : public ExpiringVisitsReader {
  public:
-  virtual bool Read(base::Time end_time,
-                    HistoryDatabase* db,
-                    VisitVector* visits,
-                    int max_visits) const override {
+  bool Read(base::Time end_time,
+            HistoryDatabase* db,
+            VisitVector* visits,
+            int max_visits) const override {
     DCHECK(db) << "must have a database to operate upon";
     DCHECK(visits) << "visit vector has to exist in order to populate it";