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

chrome/browser/about_flags.cc

 // 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.
 
 #include "chrome/browser/about_flags.h"
 
 #include <algorithm>
 #include <iterator>
 #include <map>
 #include <set>
@@ skipping 625 matching lines @@
   },
 #if defined(OS_CHROMEOS)
   {
     "no-discard-tabs",
     IDS_FLAGS_NO_DISCARD_TABS_NAME,
     IDS_FLAGS_NO_DISCARD_TABS_DESCRIPTION,
     kOsCrOS,
     SINGLE_VALUE_TYPE(switches::kNoDiscardTabs)
   },
 #endif
+  {
+    "enable-sync-signing",
+    IDS_ENABLE_SYNC_SIGNIN_NAME,
+    IDS_ENABLE_SYNC_SIGNIN_DESCRIPTION,
+    kOsAll,
+    SINGLE_VALUE_TYPE(switches::kEnableSyncSignin)
+  },
 };
 
 const Experiment* experiments = kExperiments;
 size_t num_experiments = arraysize(kExperiments);
 
 // Stores and encapsulates the little state that about:flags has.
 class FlagsState {
  public:
   FlagsState() : needs_restart_(false) {}
   void ConvertFlagsToSwitches(PrefService* prefs, CommandLine* command_line);
@@ skipping 415 matching lines @@
 }
 
 const Experiment* GetExperiments(size_t* count) {
   *count = num_experiments;
   return experiments;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags