Standardize usage of virtual/override/final in net/

net/quic/crypto/proof_source_chromium.h

Index: net/quic/crypto/proof_source_chromium.h
diff --git a/net/quic/crypto/proof_source_chromium.h b/net/quic/crypto/proof_source_chromium.h
index 3d1849ee3e692a6f03c3666988f81778d6f72bbf..334466c46e6ac51456991b2e6cf93e4cea69431f 100644
--- a/net/quic/crypto/proof_source_chromium.h
+++ b/net/quic/crypto/proof_source_chromium.h
@@ -20,14 +20,14 @@ namespace net {
 class NET_EXPORT_PRIVATE ProofSourceChromium : public ProofSource {
  public:
   ProofSourceChromium();
-  virtual ~ProofSourceChromium() {}
+  ~ProofSourceChromium() override {}
 
   // ProofSource interface
-  virtual bool GetProof(const std::string& hostname,
-                        const std::string& server_config,
-                        bool ecdsa_ok,
-                        const std::vector<std::string>** out_certs,
-                        std::string* out_signature) override;
+  bool GetProof(const std::string& hostname,
+                const std::string& server_config,
+                bool ecdsa_ok,
+                const std::vector<std::string>** out_certs,
+                std::string* out_signature) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ProofSourceChromium);