[Sync] Implement MemoryDumpProvider.

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 <utility>
 
 #include "base/stl_util.h"
 #include "components/sync/syncable/entry_kernel.h"
@@ skipping 149 matching lines @@
 }
 
 const OrderedChildSet* ParentChildIndex::GetSiblings(EntryKernel* e) const {
   // This implies the entry is in the index.
   DCHECK(Contains(e));
   const OrderedChildSetRef siblings = GetChildSet(e);
   DCHECK(siblings && !siblings->empty());
   return siblings.get();
 }
 
+size_t ParentChildIndex::EstimateMemoryUsage() const {
+  using base::trace_event::EstimateMemoryUsage;
+  return EstimateMemoryUsage(parent_children_map_) +
+         EstimateMemoryUsage(model_type_root_ids_) +
+         EstimateMemoryUsage(type_root_child_sets_);
+}
+
 /* static */
 bool ParentChildIndex::ShouldUseParentId(const Id& parent_id,
                                          ModelType model_type) {
   // For compatibility with legacy unit tests, in addition to hierarchical
   // entries, this returns true any entries directly under root and for entries
   // of UNSPECIFIED model type.
   return parent_id.IsRoot() || TypeSupportsHierarchy(model_type) ||
          !IsRealDataType(model_type);
 }
 
@@ skipping 25 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