Standardize usage of virtual/override/final in net/

net/disk_cache/blockfile/backend_impl_v3.cc

Index: net/disk_cache/blockfile/backend_impl_v3.cc
diff --git a/net/disk_cache/blockfile/backend_impl_v3.cc b/net/disk_cache/blockfile/backend_impl_v3.cc
index 09794d347e746926433f018f791315ae54bc5c9b..a1024b454091014bf143339b6b76ad1c4a8733b0 100644
--- a/net/disk_cache/blockfile/backend_impl_v3.cc
+++ b/net/disk_cache/blockfile/backend_impl_v3.cc
@@ -1510,8 +1510,8 @@ int BackendImplV3::DoomEntriesSince(base::Time initial_time,
 
 class BackendImplV3::NotImplementedIterator : public Backend::Iterator {
  public:
-  virtual int OpenNextEntry(disk_cache::Entry** next_entry,
-                            const net::CompletionCallback& callback) override {
+  int OpenNextEntry(disk_cache::Entry** next_entry,
+                    const net::CompletionCallback& callback) override {
     return net::ERR_NOT_IMPLEMENTED;
   }
 };