[Sync] Add full history sync experiment

sync/internal_api/sync_manager_impl.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 "sync/internal_api/sync_manager_impl.h"
 
 #include <string>
 
 #include "base/base64.h"
 #include "base/bind.h"
@@ skipping 1341 matching lines @@
   ReadNode autofill_culling_node(&trans);
   if (autofill_culling_node.InitByClientTagLookup(
           syncer::EXPERIMENTS,
           syncer::kAutofillCullingTag) == BaseNode::INIT_OK &&
       autofill_culling_node.GetExperimentsSpecifics().
           autofill_culling().enabled()) {
     experiments->autofill_culling = true;
     found_experiment = true;
   }
 
+  ReadNode full_history_sync_node(&trans);
+  if (full_history_sync_node.InitByClientTagLookup(
+          syncer::EXPERIMENTS,
+          syncer::kFullHistorySyncTag) == BaseNode::INIT_OK &&
+      full_history_sync_node.GetExperimentsSpecifics().
+          history_delete_directives().enabled()) {
+    experiments->full_history_sync = true;
+    found_experiment = true;
+  }
+
   return found_experiment;
 }
 
 bool SyncManagerImpl::HasUnsyncedItems() {
   ReadTransaction trans(FROM_HERE, GetUserShare());
   return (trans.GetWrappedTrans()->directory()->unsynced_entity_count() != 0);
 }
 
 SyncEncryptionHandler* SyncManagerImpl::GetEncryptionHandler() {
   return sync_encryption_handler_.get();
 }
 
 // static.
 int SyncManagerImpl::GetDefaultNudgeDelay() {
   return kDefaultNudgeDelayMilliseconds;
 }
 
 // static.
 int SyncManagerImpl::GetPreferencesNudgeDelay() {
   return kPreferencesNudgeDelayMilliseconds;
 }
 
 }  // namespace syncer