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

net/tools/quic/test_tools/mock_epoll_server.h

Index: net/tools/quic/test_tools/mock_epoll_server.h
diff --git a/net/tools/quic/test_tools/mock_epoll_server.h b/net/tools/quic/test_tools/mock_epoll_server.h
index b3b312ef4509d1998891c5ec2f4df892bd83fd64..742a957d882296e582c03db9493eda9ce88a347a 100644
--- a/net/tools/quic/test_tools/mock_epoll_server.h
+++ b/net/tools/quic/test_tools/mock_epoll_server.h
@@ -19,10 +19,10 @@ namespace test {
 class FakeTimeEpollServer : public EpollServer {
  public:
   FakeTimeEpollServer();
-  virtual ~FakeTimeEpollServer();
+  ~FakeTimeEpollServer() override;
 
   // Replaces the EpollServer NowInUsec.
-  virtual int64 NowInUsec() const override;
+  int64 NowInUsec() const override;
 
   void set_now_in_usec(int64 nius) { now_in_usec_ = nius; }
 
@@ -52,7 +52,7 @@ class MockEpollServer : public FakeTimeEpollServer {
   typedef base::hash_multimap<int64, struct epoll_event> EventQueue;
 
   MockEpollServer();
-  virtual ~MockEpollServer();
+  ~MockEpollServer() override;
 
   // time_in_usec is the time at which the event specified
   // by 'ee' will be delivered. Note that it -is- possible
@@ -85,16 +85,16 @@ class MockEpollServer : public FakeTimeEpollServer {
  protected:  // functions
   // These functions do nothing here, as we're not actually
   // using the epoll_* syscalls.
-  virtual void DelFD(int fd) const override {}
-  virtual void AddFD(int fd, int event_mask) const override {}
-  virtual void ModFD(int fd, int event_mask) const override {}
+  void DelFD(int fd) const override {}
+  void AddFD(int fd, int event_mask) const override {}
+  void ModFD(int fd, int event_mask) const override {}
 
   // Replaces the epoll_server's epoll_wait_impl.
-  virtual int epoll_wait_impl(int epfd,
-                              struct epoll_event* events,
-                              int max_events,
-                              int timeout_in_ms) override;
-  virtual void SetNonblocking (int fd) override {}
+  int epoll_wait_impl(int epfd,
+                      struct epoll_event* events,
+                      int max_events,
+                      int timeout_in_ms) override;
+  void SetNonblocking(int fd) override {}
 
  private:  // members
   EventQueue event_queue_;