Update from https://crrev.com/309717

sandbox/linux/seccomp-bpf/syscall_unittest.cc

 // 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.
 
 #include "sandbox/linux/seccomp-bpf/syscall.h"
 
 #include <asm/unistd.h>
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <sys/syscall.h>
@@ skipping 90 matching lines @@
   std::vector<uint64_t>* const seen_syscall_args =
       static_cast<std::vector<uint64_t>*>(aux);
   BPF_ASSERT(arraysize(args.args) == 6);
   seen_syscall_args->assign(args.args, args.args + arraysize(args.args));
   return -ENOMEM;
 }
 
 class CopyAllArgsOnUnamePolicy : public bpf_dsl::Policy {
  public:
   explicit CopyAllArgsOnUnamePolicy(std::vector<uint64_t>* aux) : aux_(aux) {}
-  virtual ~CopyAllArgsOnUnamePolicy() {}
+  ~CopyAllArgsOnUnamePolicy() override {}
 
-  virtual ResultExpr EvaluateSyscall(int sysno) const override {
+  ResultExpr EvaluateSyscall(int sysno) const override {
     DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
     if (sysno == __NR_uname) {
       return Trap(CopySyscallArgsToAux, aux_);
     } else {
       return Allow();
     }
   }
 
  private:
   std::vector<uint64_t>* aux_;
@@ skipping 108 matching lines @@
 
   // Clean up
   EXPECT_EQ(0, Syscall::Call(__NR_munmap, addr2, 8192L));
   EXPECT_EQ(0, Syscall::Call(__NR_munmap, addr3, 4096L));
   EXPECT_EQ(0, IGNORE_EINTR(Syscall::Call(__NR_close, fd)));
 }
 
 }  // namespace
 
 }  // namespace sandbox