Update from https://crrev.com/309415

net/socket/client_socket_pool_base.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // A ClientSocketPoolBase is used to restrict the number of sockets open at
 // a time.  It also maintains a list of idle persistent sockets for reuse.
 // Subclasses of ClientSocketPool should compose ClientSocketPoolBase to handle
 // the core logic of (1) restricting the number of active (connected or
 // connecting) sockets per "group" (generally speaking, the hostname), (2)
 // maintaining a per-group list of idle, persistent sockets for reuse, and (3)
@@ skipping 841 matching lines @@
 
     virtual scoped_ptr<ConnectJob> NewConnectJob(
         const std::string& group_name,
         const internal::ClientSocketPoolBaseHelper::Request& request,
         ConnectJob::Delegate* delegate) const override {
       const Request& casted_request = static_cast<const Request&>(request);
       return connect_job_factory_->NewConnectJob(
           group_name, casted_request, delegate);
     }
 
-    virtual base::TimeDelta ConnectionTimeout() const {
+    base::TimeDelta ConnectionTimeout() const override {
       return connect_job_factory_->ConnectionTimeout();
     }
 
     const scoped_ptr<ConnectJobFactory> connect_job_factory_;
   };
 
   // Histograms for the pool
   ClientSocketPoolHistograms* const histograms_;
   internal::ClientSocketPoolBaseHelper helper_;
 
   DISALLOW_COPY_AND_ASSIGN(ClientSocketPoolBase);
 };
 
 }  // namespace net
 
 #endif  // NET_SOCKET_CLIENT_SOCKET_POOL_BASE_H_