google_apis/gaia: Fix more clang warnings about missing virtual and OVERRIDE annotations.

google_apis/gaia/gaia_oauth_client.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "google_apis/gaia/gaia_oauth_client.h"
 
 #include "base/json/json_reader.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/values.h"
@@ skipping 26 matching lines @@
   void GetTokensFromAuthCode(const OAuthClientInfo& oauth_client_info,
                              const std::string& auth_code,
                              int max_retries,
                              GaiaOAuthClient::Delegate* delegate);
   void RefreshToken(const OAuthClientInfo& oauth_client_info,
                     const std::string& refresh_token,
                     int max_retries,
                     GaiaOAuthClient::Delegate* delegate);
 
   // net::URLFetcherDelegate implementation.
-  virtual void OnURLFetchComplete(const net::URLFetcher* source);
+  virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
 
  private:
   friend class base::RefCountedThreadSafe<Core>;
   virtual ~Core() {}
 
   void MakeGaiaRequest(const std::string& post_body,
                        int max_retries,
                        GaiaOAuthClient::Delegate* delegate);
   void HandleResponse(const net::URLFetcher* source,
                       bool* should_retry_request);
@@ skipping 141 matching lines @@
                                    const std::string& refresh_token,
                                    int max_retries,
                                    Delegate* delegate) {
   return core_->RefreshToken(oauth_client_info,
                              refresh_token,
                              max_retries,
                              delegate);
 }
 
 }  // namespace gaia