Standardize usage of virtual/override/final specifiers.

components/nacl/loader/sandbox_linux/nacl_bpf_sandbox_linux.cc

Index: components/nacl/loader/sandbox_linux/nacl_bpf_sandbox_linux.cc
diff --git a/components/nacl/loader/sandbox_linux/nacl_bpf_sandbox_linux.cc b/components/nacl/loader/sandbox_linux/nacl_bpf_sandbox_linux.cc
index 9bd807e473bdfc252cb56ef15538ed5620be6451..0a8085ab0631bc41bef850718b497be8f47de5c1 100644
--- a/components/nacl/loader/sandbox_linux/nacl_bpf_sandbox_linux.cc
+++ b/components/nacl/loader/sandbox_linux/nacl_bpf_sandbox_linux.cc
@@ -38,10 +38,10 @@ class NaClBPFSandboxPolicy : public sandbox::bpf_dsl::Policy {
  public:
   NaClBPFSandboxPolicy()
       : baseline_policy_(content::GetBPFSandboxBaselinePolicy()) {}
-  virtual ~NaClBPFSandboxPolicy() {}
+  ~NaClBPFSandboxPolicy() override {}
 
-  virtual ResultExpr EvaluateSyscall(int system_call_number) const override;
-  virtual ResultExpr InvalidSyscall() const override {
+  ResultExpr EvaluateSyscall(int system_call_number) const override;
+  ResultExpr InvalidSyscall() const override {
     return baseline_policy_->InvalidSyscall();
   }