Warn on missing OVERRIDE/virtual everywhere, not just in header files.

net/quic/test_tools/crypto_test_utils.cc

Index: net/quic/test_tools/crypto_test_utils.cc
diff --git a/net/quic/test_tools/crypto_test_utils.cc b/net/quic/test_tools/crypto_test_utils.cc
index 332057c80d4f615f2f1a83a3de50a26b2a9badc7..9504949257292502ecc752720ee3b7c9a8eeb359 100644
--- a/net/quic/test_tools/crypto_test_utils.cc
+++ b/net/quic/test_tools/crypto_test_utils.cc
@@ -45,11 +45,12 @@ class CryptoFramerVisitor : public CryptoFramerVisitorInterface {
       : error_(false) {
   }
 
-  void OnError(CryptoFramer* framer) {
+  virtual void OnError(CryptoFramer* framer) OVERRIDE {
     error_ = true;
   }
 
-  void OnHandshakeMessage(const CryptoHandshakeMessage& message) {
+  virtual void OnHandshakeMessage(
+      const CryptoHandshakeMessage& message) OVERRIDE {
     messages_.push_back(message);
   }