Standardize usage of virtual/override/final in google_apis/

google_apis/gcm/engine/checkin_request.h

Index: google_apis/gcm/engine/checkin_request.h
diff --git a/google_apis/gcm/engine/checkin_request.h b/google_apis/gcm/engine/checkin_request.h
index af9e48f8983c3e80746d0d3dcdf4e29461d6da04..e3ad8edd9a050c324dc1d09ffb325e84ab3c9836 100644
--- a/google_apis/gcm/engine/checkin_request.h
+++ b/google_apis/gcm/engine/checkin_request.h
@@ -64,12 +64,12 @@ class GCM_EXPORT CheckinRequest : public net::URLFetcherDelegate {
                  const CheckinRequestCallback& callback,
                  net::URLRequestContextGetter* request_context_getter,
                  GCMStatsRecorder* recorder);
-  virtual ~CheckinRequest();
+  ~CheckinRequest() override;
 
   void Start();
 
   // URLFetcherDelegate implementation.
-  virtual void OnURLFetchComplete(const net::URLFetcher* source) override;
+  void OnURLFetchComplete(const net::URLFetcher* source) override;
 
  private:
   // Schedules a retry attempt, informs the backoff of a previous request's