Refactor preference syncing.

chrome/browser/sync/signin_manager.cc

 // 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.
 
 #include "chrome/browser/sync/signin_manager.h"
 
 #include "base/string_util.h"
 #include "chrome/browser/net/gaia/token_service.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/net/gaia/gaia_constants.h"
 #include "chrome/common/pref_names.h"
 #include "content/common/notification_service.h"
 
 const char kGetInfoEmailKey[] = "email";
 
 SigninManager::SigninManager()
     : profile_(NULL), had_two_factor_error_(false) {}
 
 SigninManager::~SigninManager() {}
 
 // static
 void SigninManager::RegisterUserPrefs(PrefService* user_prefs) {
-  user_prefs->RegisterStringPref(prefs::kGoogleServicesUsername, "");
+  user_prefs->RegisterStringPref(prefs::kGoogleServicesUsername,
+                                 "",
+                                 PrefService::UNSYNCABLE_PREF);
 }
 
 void SigninManager::Initialize(Profile* profile) {
   profile_ = profile;
   username_ = profile_->GetPrefs()->GetString(prefs::kGoogleServicesUsername);
   profile_->GetTokenService()->Initialize(
       GaiaConstants::kChromeSource, profile_);
   if (!username_.empty()) {
     profile_->GetTokenService()->LoadTokensFromDB();
   }
@@ skipping 117 matching lines @@
   bool invalid_gaia = error.state() ==
       GoogleServiceAuthError::INVALID_GAIA_CREDENTIALS;
   if (error.state() == GoogleServiceAuthError::TWO_FACTOR ||
       (had_two_factor_error_ && invalid_gaia)) {
     had_two_factor_error_ = true;
     return;
   }
 
   SignOut();
 }