Remove dependency on server generated type root folders

sync/syncable/syncable_id.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/syncable/syncable_id.h"
 
 #include <iosfwd>
 
 #include "base/logging.h"
 #include "base/values.h"
@@ skipping 17 matching lines @@
   // Currently root is the string "0". We need to decide on a true value.
   // "" would be convenient here, as the IsRoot call would not be needed.
   DCHECK(!IsNull());
   if (IsRoot())
     return "0";
   return s_.substr(1);
 }
 
 Id Id::CreateFromServerId(const string& server_id) {
   Id id;
-  if (server_id == "0")
-    id.s_ = "r";
-  else
-    id.s_ = string("s") + server_id;
+  if (!server_id.empty()) {

[Nicolas Zea, 2015/01/26 23:21:53]

This just for testing right? Or was there another reason for this?

[stanisc, 2015/01/28 07:30:06]

Once the server transition is done, most of parent ID strings in server updates
would be empty. 
Checking it everywhere this function is called would be tedious.
Checking it here seemed like a much more elegant solution.

+    if (server_id == "0")
+      id.s_ = "r";
+    else
+      id.s_ = string("s") + server_id;
+  }
   return id;
 }
 
 Id Id::CreateFromClientString(const string& local_id) {
   Id id;
-  if (local_id == "0")
-    id.s_ = "r";
-  else
-    id.s_ = string("c") + local_id;
+  if (!local_id.empty()) {
+    if (local_id == "0")
+      id.s_ = "r";
+    else
+      id.s_ = string("c") + local_id;
+  }
   return id;
 }
 
 Id Id::GetRoot() {
   Id id;
   id.s_ = "r";
   return id;
 }
 
 Id Id::GetLexicographicSuccessor() const {
   // The successor of a string is given by appending the least
   // character in the alphabet.
   Id id = *this;
   id.s_.push_back(0);
   return id;
 }
 
 // static
 Id Id::GetLeastIdForLexicographicComparison() {
   Id id;
   id.s_.clear();
   return id;
 }
 
 }  // namespace syncable
 }  // namespace syncer