Sync UI: Add a flag to enable the new signin flow.

chrome/common/chrome_switches.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.
 
 // Defines all the command-line switches used by Chrome.
 
 #ifndef CHROME_COMMON_CHROME_SWITCHES_H_
 #define CHROME_COMMON_CHROME_SWITCHES_H_
 #pragma once
 
@@ skipping 151 matching lines @@
 extern const char kEnablePanels[];
 extern const char kEnablePasswordGeneration[];
 extern const char kEnablePlatformApps[];
 extern const char kEnablePnacl[];
 extern const char kEnableProfiling[];
 extern const char kEnableResourceContentSettings[];
 extern const char kEnableSdch[];
 extern const char kEnableSpdy3[];
 extern const char kEnableSpdyFlowControl[];
 extern const char kEnableSuggestionsTabPage[];
+extern const char kEnableSyncSignin[];
 extern const char kEnableSyncTabs[];
 extern const char kDisableSyncTabs[];
 extern const char kEnableSyncTabsForOtherClients[];
 extern const char kEnableTabGroupsContextMenu[];
 extern const char kEnableWatchdog[];
 extern const char kEnableWebsiteSettings[];
 extern const char kEnableWebSocketOverSpdy[];
 extern const char kEnableWebStoreLink[];
 extern const char kExperimentalSpellcheckerFeatures[];
 extern const char kExplicitlyAllowedPorts[];
@@ skipping 228 matching lines @@
 #else
 extern const char kEnablePrintPreview[];
 #endif
 
 // DON'T ADD RANDOM STUFF HERE. Put it in the main section above in
 // alphabetical order, or in one of the ifdefs (also in order in each section).
 
 }  // namespace switches
 
 #endif  // CHROME_COMMON_CHROME_SWITCHES_H_