Standardize usage of virtual/override/final in net/

net/http/mock_http_cache.cc

Index: net/http/mock_http_cache.cc
diff --git a/net/http/mock_http_cache.cc b/net/http/mock_http_cache.cc
index 325454e541a321ef41f399e2d1034940e3458914..4ca542ea5cb3c76c61e79620faaaa4f8e856cc3e 100644
--- a/net/http/mock_http_cache.cc
+++ b/net/http/mock_http_cache.cc
@@ -459,8 +459,8 @@ int MockDiskCache::DoomEntriesSince(const base::Time initial_time,
 
 class MockDiskCache::NotImplementedIterator : public 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;
   }
 };