sync: move internal_api components used by chrome/browser into internal_api/public

sync/internal_api/public/util/experiments.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 SYNC_UTIL_EXPERIMENTS_
 #define SYNC_UTIL_EXPERIMENTS_
 #pragma once
 
 #include "sync/internal_api/public/syncable/model_type.h"
 
 namespace browser_sync {
 
 // A structure to hold the enable status of experimental sync features.
 struct Experiments {
   Experiments() : sync_tab_favicons(false) {}
 
   bool Matches(const Experiments& rhs) {
     return (sync_tab_favicons == rhs.sync_tab_favicons);
   }
 
   // Enable syncing of favicons within tab sync (only has an effect if tab sync
   // is already enabled). This takes effect on the next restart.
   bool sync_tab_favicons;
 };
 
 }
 
 #endif  // SYNC_UTIL_EXPERIMENTS_