Convert SigninTracker to use OAuth2TokenService notifications

chrome/browser/signin/token_service.h

 // 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.
 //
 // The TokenService will supply authentication tokens for any service that
 // needs it, such as sync. Whenever the user logs in, a controller watching
 // the token service is expected either to call ClientLogin to derive a new
 // SID and LSID, or to use GAIA OAuth requests to derive an OAuth1 access
 // token for the OAuthLogin scope.  Whenever such credentials are available,
 // the TokenService should be updated with new credentials.  The controller
@@ skipping 117 matching lines @@
   // Update ClientLogin credentials in the token service.
   // Afterwards you can StartFetchingTokens.
   void UpdateCredentials(
       const GaiaAuthConsumer::ClientLoginResult& credentials);
 
   // Update credentials in the token service with oauth2 tokens.
   // Afterwards you can StartFetchingTokens.
   void UpdateCredentialsWithOAuth2(
       const GaiaAuthConsumer::ClientOAuthResult& credentials);
 
+  // Remove the OAuth2 token.
+  void ClearOAuth2Credentials();
+
   // Terminate any running requests and reset the TokenService to a clean
   // slate. Resets in memory structures. Does not modify the DB.
   // When this is done, no tokens will be left in memory and no
   // user credentials will be left. Useful if a user is logging out.
   // Initialize doesn't need to be called again but UpdateCredentials does.
   void ResetCredentialsInMemory();
 
   // Async load all tokens for services we know of from the DB.
   // You should do this at startup. Optionally you can do it again
   // after you reset in memory credentials.
@@ skipping 110 matching lines @@
 
   friend class TokenServiceTest;
   FRIEND_TEST_ALL_PREFIXES(TokenServiceTest, LoadTokensIntoMemoryBasic);
   FRIEND_TEST_ALL_PREFIXES(TokenServiceTest, LoadTokensIntoMemoryAdvanced);
   FRIEND_TEST_ALL_PREFIXES(TokenServiceTest, FullIntegrationNewServicesAdded);
 
   DISALLOW_COPY_AND_ASSIGN(TokenService);
 };
 
 #endif  // CHROME_BROWSER_SIGNIN_TOKEN_SERVICE_H_