Update from https://crrev.com/309717

sandbox/linux/seccomp-bpf/bpf_tests_unittest.cc

Index: sandbox/linux/seccomp-bpf/bpf_tests_unittest.cc
diff --git a/sandbox/linux/seccomp-bpf/bpf_tests_unittest.cc b/sandbox/linux/seccomp-bpf/bpf_tests_unittest.cc
index 192e68ddfc9d5a2cb52e92d4bd7f1908ed0ceb41..9727d28f04288e9332f757d0558926218f48d52c 100644
--- a/sandbox/linux/seccomp-bpf/bpf_tests_unittest.cc
+++ b/sandbox/linux/seccomp-bpf/bpf_tests_unittest.cc
@@ -46,9 +46,9 @@ class EmptyClassTakingPolicy : public bpf_dsl::Policy {
     BPF_ASSERT(fourty_two);
     BPF_ASSERT(FourtyTwo::kMagicValue == fourty_two->value());
   }
-  virtual ~EmptyClassTakingPolicy() {}
+  ~EmptyClassTakingPolicy() override {}
 
-  virtual ResultExpr EvaluateSyscall(int sysno) const override {
+  ResultExpr EvaluateSyscall(int sysno) const override {
     DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
     return Allow();
   }
@@ -84,13 +84,13 @@ TEST(BPFTest, BPFTesterCompatibilityDelegateLeakTest) {
 class EnosysPtracePolicy : public bpf_dsl::Policy {
  public:
   EnosysPtracePolicy() { my_pid_ = sys_getpid(); }
-  virtual ~EnosysPtracePolicy() {
+  ~EnosysPtracePolicy() override {
     // Policies should be able to bind with the process on which they are
     // created. They should never be created in a parent process.
     BPF_ASSERT_EQ(my_pid_, sys_getpid());
   }
 
-  virtual ResultExpr EvaluateSyscall(int system_call_number) const override {
+  ResultExpr EvaluateSyscall(int system_call_number) const override {
     CHECK(SandboxBPF::IsValidSyscallNumber(system_call_number));
     if (system_call_number == __NR_ptrace) {
       // The EvaluateSyscall function should run in the process that created
@@ -110,12 +110,12 @@ class EnosysPtracePolicy : public bpf_dsl::Policy {
 class BasicBPFTesterDelegate : public BPFTesterDelegate {
  public:
   BasicBPFTesterDelegate() {}
-  virtual ~BasicBPFTesterDelegate() {}
+  ~BasicBPFTesterDelegate() override {}
 
-  virtual scoped_ptr<bpf_dsl::Policy> GetSandboxBPFPolicy() override {
+  scoped_ptr<bpf_dsl::Policy> GetSandboxBPFPolicy() override {
     return scoped_ptr<bpf_dsl::Policy>(new EnosysPtracePolicy());
   }
-  virtual void RunTestFunction() override {
+  void RunTestFunction() override {
     errno = 0;
     int ret = ptrace(PTRACE_TRACEME, -1, NULL, NULL);
     BPF_ASSERT(-1 == ret);