Use a distinct source parameter on gaia endpoints for the reconcilor.

google_apis/gaia/gaia_auth_fetcher.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.
 
 #ifndef GOOGLE_APIS_GAIA_GAIA_AUTH_FETCHER_H_
 #define GOOGLE_APIS_GAIA_GAIA_AUTH_FETCHER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 371 matching lines @@
       int load_flags,
       net::URLFetcherDelegate* delegate);
 
   // From a URLFetcher result, generate an appropriate error.
   // From the API documentation, both IssueAuthToken and ClientLogin have
   // the same error returns.
   static GoogleServiceAuthError GenerateAuthError(
       const std::string& data,
       const net::URLRequestStatus& status);
 
-  // These fields are common to GaiaAuthFetcher, same every request
+  // These fields are common to GaiaAuthFetcher, same every request.
   GaiaAuthConsumer* const consumer_;
   net::URLRequestContextGetter* const getter_;
   std::string source_;
   const GURL client_login_gurl_;
   const GURL issue_auth_token_gurl_;
   const GURL oauth2_token_gurl_;
   const GURL oauth2_revoke_gurl_;
   const GURL get_user_info_gurl_;
   const GURL merge_session_gurl_;
   const GURL uberauth_token_gurl_;
@@ skipping 23 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(GaiaAuthFetcherTest, ParseOAuth2TokenPairResponse);
   FRIEND_TEST_ALL_PREFIXES(GaiaAuthFetcherTest, ClientOAuthSuccess);
   FRIEND_TEST_ALL_PREFIXES(GaiaAuthFetcherTest, ClientOAuthWithQuote);
   FRIEND_TEST_ALL_PREFIXES(GaiaAuthFetcherTest, ClientOAuthChallengeSuccess);
   FRIEND_TEST_ALL_PREFIXES(GaiaAuthFetcherTest, ClientOAuthChallengeQuote);
 
   DISALLOW_COPY_AND_ASSIGN(GaiaAuthFetcher);
 };
 
 #endif  // GOOGLE_APIS_GAIA_GAIA_AUTH_FETCHER_H_