[Sync] Implement EstimateMemoryUsage for SharedModelTypeProcessor and ModelTypeWorker

components/sync/model/entity_data.h

 // Copyright 2015 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.
 
 #ifndef COMPONENTS_SYNC_MODEL_ENTITY_DATA_H_
 #define COMPONENTS_SYNC_MODEL_ENTITY_DATA_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 61 matching lines @@
   // specifics hasn't been set.
   bool is_deleted() const { return specifics.ByteSize() == 0; }
 
   // Transfers this struct's data to EntityDataPtr.
   // The return value must be assigned into another EntityDataPtr.
   EntityDataPtr PassToPtr() WARN_UNUSED_RESULT;
 
   // Dumps all info into a DictionaryValue and returns it.
   std::unique_ptr<base::DictionaryValue> ToDictionaryValue();
 
+  // Returns the estimate of dynamically allocated memory in bytes.
+  size_t EstimateMemoryUsage() const;
+
  private:
   friend struct EntityDataTraits;
   // Used to transfer the data without copying.
   void Swap(EntityData* other);
 
   DISALLOW_COPY_AND_ASSIGN(EntityData);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_MODEL_ENTITY_DATA_H_