Enable web-based sign in flow by default. Can use command line argument

chrome/browser/ui/sync/one_click_signin_helper.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 CHROME_BROWSER_UI_SYNC_ONE_CLICK_SIGNIN_HELPER_H_
 #define CHROME_BROWSER_UI_SYNC_ONE_CLICK_SIGNIN_HELPER_H_
 
 #include <string>
 
 #include "base/gtest_prod_util.h"
@@ skipping 79 matching lines @@
   // Initialize a finch experiment for the infobar.
   static void InitializeFieldTrial();
 
   // Looks for the Google-Accounts-SignIn response header, and if found,
   // tries to display an infobar in the tab contents identified by the
   // child/route id.
   static void ShowInfoBarIfPossible(net::URLRequest* request,
                                     int child_id,
                                     int route_id);
 
+  // Returns true if a web-based sign in flow should be used.
+  static bool UseWebBasedSigninFlow();
+
  private:
   explicit OneClickSigninHelper(content::WebContents* web_contents);
   friend class content::WebContentsUserData<OneClickSigninHelper>;
   FRIEND_TEST_ALL_PREFIXES(OneClickSigninHelperIOTest, CanOfferOnIOThread);
   FRIEND_TEST_ALL_PREFIXES(OneClickSigninHelperIOTest,
                            CanOfferOnIOThreadIncognito);
   FRIEND_TEST_ALL_PREFIXES(OneClickSigninHelperIOTest,
                            CanOfferOnIOThreadNoIOData);
   FRIEND_TEST_ALL_PREFIXES(OneClickSigninHelperIOTest,
                            CanOfferOnIOThreadBadURL);
@@ skipping 55 matching lines @@
   AutoAccept auto_accept_;
   SyncPromoUI::Source source_;
   std::string error_message_;
 
   scoped_ptr<SigninTracker> signin_tracker_;
 
   DISALLOW_COPY_AND_ASSIGN(OneClickSigninHelper);
 };
 
 #endif  // CHROME_BROWSER_UI_SYNC_ONE_CLICK_SIGNIN_HELPER_H_