Update from https://crrev.com/309717

sandbox/linux/seccomp-bpf/trap.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.
 
 #ifndef SANDBOX_LINUX_SECCOMP_BPF_TRAP_H__
 #define SANDBOX_LINUX_SECCOMP_BPF_TRAP_H__
 
 #include <signal.h>
 #include <stdint.h>
 
 #include <map>
 
 #include "base/macros.h"
 #include "sandbox/linux/bpf_dsl/trap_registry.h"
 #include "sandbox/sandbox_export.h"
 
 namespace sandbox {
 
 // The Trap class allows a BPF filter program to branch out to user space by
 // raising a SIGSYS signal.
 // N.B.: This class does not perform any synchronization operations. If
 //   modifications are made to any of the traps, it is the caller's
 //   responsibility to ensure that this happens in a thread-safe fashion.
 //   Preferably, that means that no other threads should be running at that
 //   time. For the purposes of our sandbox, this assertion should always be
 //   true. Threads are incompatible with the seccomp sandbox anyway.
 class SANDBOX_EXPORT Trap : public bpf_dsl::TrapRegistry {
  public:
-  virtual uint16_t Add(TrapFnc fnc, const void* aux, bool safe) override;
+  uint16_t Add(TrapFnc fnc, const void* aux, bool safe) override;
 
-  virtual bool EnableUnsafeTraps() override;
+  bool EnableUnsafeTraps() override;
 
   // Registry returns the trap registry used by Trap's SIGSYS handler,
   // creating it if necessary.
   static bpf_dsl::TrapRegistry* Registry();
 
   // Registers a new trap handler and sets up the appropriate SIGSYS handler
   // as needed.
   // N.B.: This makes a permanent state change. Traps cannot be unregistered,
   //   as that would break existing BPF filters that are still active.
   // TODO(mdempsky): Deprecated; remove.
@@ skipping 50 matching lines @@
   bool has_unsafe_traps_;       // Whether unsafe traps have been enabled
 
   // Copying and assigning is unimplemented. It doesn't make sense for a
   // singleton.
   DISALLOW_COPY_AND_ASSIGN(Trap);
 };
 
 }  // namespace sandbox
 
 #endif  // SANDBOX_LINUX_SECCOMP_BPF_TRAP_H__