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

chrome/common/net/gaia/gaia_auth_consumer.h

Index: chrome/common/net/gaia/gaia_auth_consumer.h
===================================================================
--- chrome/common/net/gaia/gaia_auth_consumer.h	(revision 110361)
+++ chrome/common/net/gaia/gaia_auth_consumer.h	(working copy)
@@ -42,6 +42,11 @@
   virtual void OnIssueAuthTokenFailure(const std::string& service,
                                        const GoogleServiceAuthError& error) {}
 
+  virtual void OnOAuthLoginTokenSuccess(const std::string& refresh_token,
+                                        const std::string& access_token,
+                                        int expires_in_secs) {}
+  virtual void OnOAuthLoginTokenFailure(const GoogleServiceAuthError& error) {}
+
   virtual void OnGetUserInfoSuccess(const std::string& key,
                                     const std::string& value) {}
   virtual void OnGetUserInfoKeyNotFound(const std::string& key) {}