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

net/tools/quic/test_tools/packet_dropping_test_writer.h

Index: net/tools/quic/test_tools/packet_dropping_test_writer.h
diff --git a/net/tools/quic/test_tools/packet_dropping_test_writer.h b/net/tools/quic/test_tools/packet_dropping_test_writer.h
index 29a21a823cce7360f3c987759ce97aa4cedb6f21..842d70ee209933565a51750d47c550e56464b1f0 100644
--- a/net/tools/quic/test_tools/packet_dropping_test_writer.h
+++ b/net/tools/quic/test_tools/packet_dropping_test_writer.h
@@ -36,7 +36,7 @@ class PacketDroppingTestWriter : public QuicPacketWriterWrapper {
 
   PacketDroppingTestWriter();
 
-  virtual ~PacketDroppingTestWriter();
+  ~PacketDroppingTestWriter() override;
 
   // Must be called before blocking, reordering or delaying (loss is OK). May be
   // called after connecting if the helper is not available before.
@@ -45,15 +45,14 @@ class PacketDroppingTestWriter : public QuicPacketWriterWrapper {
   void Initialize(QuicEpollConnectionHelper* helper, Delegate* on_can_write);
 
   // QuicPacketWriter methods:
-  virtual WriteResult WritePacket(
-      const char* buffer,
-      size_t buf_len,
-      const IPAddressNumber& self_address,
-      const IPEndPoint& peer_address) override;
+  WriteResult WritePacket(const char* buffer,
+                          size_t buf_len,
+                          const IPAddressNumber& self_address,
+                          const IPEndPoint& peer_address) override;
 
-  virtual bool IsWriteBlocked() const override;
+  bool IsWriteBlocked() const override;
 
-  virtual void SetWritable() override;
+  void SetWritable() override;
 
   // Writes out any packet which should have been sent by now
   // to the contained writer and returns the time