Update from chromium https://crrev.com/301725/

net/tools/quic/quic_epoll_connection_helper.h

Index: net/tools/quic/quic_epoll_connection_helper.h
diff --git a/net/tools/quic/quic_epoll_connection_helper.h b/net/tools/quic/quic_epoll_connection_helper.h
index 9ca2cf8f01f22e90a5a598a187defda6af91774c..66a27bb5e96e40c55bd6f5809407ba1fe7fc9e70 100644
--- a/net/tools/quic/quic_epoll_connection_helper.h
+++ b/net/tools/quic/quic_epoll_connection_helper.h
@@ -33,12 +33,12 @@ class TimeoutAlarm;
 class QuicEpollConnectionHelper : public QuicConnectionHelperInterface {
  public:
   explicit QuicEpollConnectionHelper(EpollServer* eps);
-  virtual ~QuicEpollConnectionHelper();
+  ~QuicEpollConnectionHelper() override;
 
   // QuicEpollConnectionHelperInterface
-  virtual const QuicClock* GetClock() const override;
-  virtual QuicRandom* GetRandomGenerator() override;
-  virtual QuicAlarm* CreateAlarm(QuicAlarm::Delegate* delegate) override;
+  const QuicClock* GetClock() const override;
+  QuicRandom* GetRandomGenerator() override;
+  QuicAlarm* CreateAlarm(QuicAlarm::Delegate* delegate) override;
 
   EpollServer* epoll_server() { return epoll_server_; }