sync: Specialize functions that fetch type root

sync/internal_api/write_node.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/public/write_node.h"
 
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "sync/internal_api/public/base_transaction.h"
@@ skipping 292 matching lines @@
 
   entry_ = new syncable::MutableEntry(transaction_->GetWrappedWriteTrans(),
                                       syncable::GET_BY_CLIENT_TAG, hash);
   if (!entry_->good())
     return INIT_FAILED_ENTRY_NOT_GOOD;
   if (entry_->GetIsDel())
     return INIT_FAILED_ENTRY_IS_DEL;
   return DecryptIfNecessary() ? INIT_OK : INIT_FAILED_DECRYPT_IF_NECESSARY;
 }
 
-BaseNode::InitByLookupResult WriteNode::InitByTagLookup(
-    const std::string& tag) {
+BaseNode::InitByLookupResult WriteNode::InitTypeRoot(ModelType type) {
   DCHECK(!entry_) << "Init called twice";
-  if (tag.empty())
+  if (!IsRealDataType(type))
     return INIT_FAILED_PRECONDITION;
   entry_ = new syncable::MutableEntry(transaction_->GetWrappedWriteTrans(),
-                                      syncable::GET_BY_SERVER_TAG, tag);
+                                      syncable::GET_TYPE_ROOT, type);
   if (!entry_->good())
     return INIT_FAILED_ENTRY_NOT_GOOD;
   if (entry_->GetIsDel())
     return INIT_FAILED_ENTRY_IS_DEL;
   ModelType model_type = GetModelType();
   DCHECK_EQ(model_type, NIGORI);
   return INIT_OK;
 }
 
 // Create a new node with default properties, and bind this WriteNode to it.
@@ skipping 175 matching lines @@
   MarkForSyncing();
 
   return true;
 }
 
 void WriteNode::MarkForSyncing() {
   syncable::MarkForSyncing(entry_);
 }
 
 }  // namespace syncer