Sync: Handle empty (implicit) ParentId in GetPredecessorId and GetSuccessorId

sync/syncable/directory.cc

 // Copyright 2013 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/directory.h"
 
 #include <algorithm>
 #include <iterator>
 
 #include "base/base64.h"
@@ skipping 316 matching lines @@
     return;  // This directory has no children.
 
   // Add our children to the list of items to be traversed.
   child_sets->push_back(descendants);
 }
 
 int Directory::GetPositionIndex(
     BaseTransaction* trans,
     EntryKernel* kernel) const {
   const OrderedChildSet* siblings =
-      kernel_->parent_child_index.GetChildren(kernel->ref(PARENT_ID));
+      kernel_->parent_child_index.GetSiblings(kernel);
 
   OrderedChildSet::const_iterator it = siblings->find(kernel);
   return std::distance(siblings->begin(), it);
 }
 
 bool Directory::InsertEntry(BaseWriteTransaction* trans, EntryKernel* entry) {
   ScopedKernelLock lock(this);
   return InsertEntry(lock, trans, entry);
 }
 
@@ skipping 1005 matching lines @@
   if (!children)
     return Id();
 
   return (*children->begin())->ref(ID);
 }
 
 syncable::Id Directory::GetPredecessorId(EntryKernel* e) {
   ScopedKernelLock lock(this);
 
   DCHECK(ParentChildIndex::ShouldInclude(e));
-  const OrderedChildSet* children =
-      kernel_->parent_child_index.GetChildren(e->ref(PARENT_ID));
-  DCHECK(children && !children->empty());
-  OrderedChildSet::const_iterator i = children->find(e);
-  DCHECK(i != children->end());
+  const OrderedChildSet* siblings = kernel_->parent_child_index.GetSiblings(e);
+  OrderedChildSet::const_iterator i = siblings->find(e);
+  DCHECK(i != siblings->end());
 
-  if (i == children->begin()) {
+  if (i == siblings->begin()) {
     return Id();
   } else {
     i--;
     return (*i)->ref(ID);
   }
 }
 
 syncable::Id Directory::GetSuccessorId(EntryKernel* e) {
   ScopedKernelLock lock(this);
 
   DCHECK(ParentChildIndex::ShouldInclude(e));
-  const OrderedChildSet* children =
-      kernel_->parent_child_index.GetChildren(e->ref(PARENT_ID));
-  DCHECK(children && !children->empty());
-  OrderedChildSet::const_iterator i = children->find(e);
-  DCHECK(i != children->end());
+  const OrderedChildSet* siblings = kernel_->parent_child_index.GetSiblings(e);
+  OrderedChildSet::const_iterator i = siblings->find(e);
+  DCHECK(i != siblings->end());
 
   i++;
-  if (i == children->end()) {
+  if (i == siblings->end()) {
     return Id();
   } else {
     return (*i)->ref(ID);
   }
 }
 
 // TODO(rlarocque): Remove all support for placing ShouldMaintainPosition()
 // items as siblings of items that do not maintain postions.  It is required
 // only for tests.  See crbug.com/178282.
 void Directory::PutPredecessor(EntryKernel* e, EntryKernel* predecessor) {
@@ skipping 146 matching lines @@
   // TODO(maniscalco): Eliminate redundant metadata storage (bug 415203).
   std::set_difference(not_on_server_id_set.begin(),
                       not_on_server_id_set.end(),
                       on_server_id_set.begin(),
                       on_server_id_set.end(),
                       std::inserter(*id_set, id_set->end()));
 }
 
 }  // namespace syncable
 }  // namespace syncer