Revert 111270 - Part 1 of work to do user sign in based on OAuth2:

chrome/common/net/gaia/oauth2_access_token_consumer.h

Index: chrome/common/net/gaia/oauth2_access_token_consumer.h
===================================================================
--- chrome/common/net/gaia/oauth2_access_token_consumer.h	(revision 111276)
+++ chrome/common/net/gaia/oauth2_access_token_consumer.h	(working copy)
@@ -1,23 +0,0 @@
-// Copyright (c) 2011 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.
-
-#ifndef CHROME_COMMON_NET_GAIA_OAUTH2_ACCESS_TOKEN_CONSUMER_H_
-#define CHROME_COMMON_NET_GAIA_OAUTH2_ACCESS_TOKEN_CONSUMER_H_
-#pragma once
-
-#include <string>
-
-class GoogleServiceAuthError;
-
-// An interface that defines the callbacks for consumers to which
-// OAuth2AccessTokenFetcher can return results.
-class OAuth2AccessTokenConsumer {
- public:
-  virtual ~OAuth2AccessTokenConsumer() {}
-
-  virtual void OnGetTokenSuccess(const std::string& access_token) {}
-  virtual void OnGetTokenFailure(const GoogleServiceAuthError& error) {}
-};
-
-#endif  // CHROME_COMMON_NET_GAIA_OAUTH2_ACCESS_TOKEN_CONSUMER_H_