[Sync] Removing duplicated includes between cc and h files.

components/sync/syncable/parent_child_index.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 "components/sync/syncable/parent_child_index.h"
 
-#include <memory>
-
 #include "base/stl_util.h"
 #include "components/sync/syncable/entry_kernel.h"
-#include "components/sync/syncable/syncable_id.h"
 
 namespace syncer {
 namespace syncable {
 
 bool ChildComparator::operator()(const EntryKernel* a,
                                  const EntryKernel* b) const {
   const UniquePosition& a_pos = a->ref(UNIQUE_POSITION);
   const UniquePosition& b_pos = b->ref(UNIQUE_POSITION);
 
   if (a_pos.IsValid() && b_pos.IsValid()) {
@@ skipping 185 matching lines @@
         OrderedChildSetRef(new OrderedChildSet());
   return type_root_child_sets_[model_type];
 }
 
 const Id& ParentChildIndex::GetModelTypeRootId(ModelType model_type) const {
   return model_type_root_ids_[model_type];
 }
 
 }  // namespace syncable
 }  // namespace syncer