Update {virtual,override,final} to follow C++11 style in chromeos.

chromeos/attestation/mock_attestation_flow.h

Index: chromeos/attestation/mock_attestation_flow.h
diff --git a/chromeos/attestation/mock_attestation_flow.h b/chromeos/attestation/mock_attestation_flow.h
index a4a26b99225a136ece5e386ecaa449b11af3fe62..efefd94f3125651e9c882a062016d5d858c95f96 100644
--- a/chromeos/attestation/mock_attestation_flow.h
+++ b/chromeos/attestation/mock_attestation_flow.h
@@ -18,17 +18,17 @@ namespace attestation {
 class FakeServerProxy : public ServerProxy {
  public:
   FakeServerProxy();
-  virtual ~FakeServerProxy();
+  ~FakeServerProxy() override;
 
   void set_result(bool result) {
     result_ = result;
   }
 
-  virtual void SendEnrollRequest(const std::string& request,
-                                 const DataCallback& callback) override;
+  void SendEnrollRequest(const std::string& request,
+                         const DataCallback& callback) override;
 
-  virtual void SendCertificateRequest(const std::string& request,
-                                      const DataCallback& callback) override;
+  void SendCertificateRequest(const std::string& request,
+                              const DataCallback& callback) override;
 
  private:
   bool result_;