[Sync] Implement EstimateMemoryUsage for SharedModelTypeProcessor and ModelTypeWorker

components/sync/engine_impl/model_type_worker.h

 // Copyright 2014 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_ENGINE_IMPL_MODEL_TYPE_WORKER_H_
 #define COMPONENTS_SYNC_ENGINE_IMPL_MODEL_TYPE_WORKER_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 80 matching lines @@
   // called when a new encryption mechanism is ready.
   void EncryptionAcceptedApplyUpdates();
 
   // Callback for when our contribution gets a response.
   void OnCommitResponse(CommitResponseDataList* response_list);
 
   // If migration the directory encounters an error partway through, we need to
   // clear the update data that has been added so far.
   void AbortMigration();
 
+  // Returns the estimate of dynamically allocated memory in bytes.
+  size_t EstimateMemoryUsage() const;
+
   base::WeakPtr<ModelTypeWorker> AsWeakPtr();
 
  private:
   using EntityMap = std::map<std::string, std::unique_ptr<WorkerEntityTracker>>;
 
   // Helper function to actually send |pending_updates_| to the processor.
   void ApplyPendingUpdates();
 
   // Returns true if this type has successfully fetched all available updates
   // from the server at least once. Our state may or may not be stale, but at
@@ skipping 88 matching lines @@
   // Whether there are outstanding encrypted updates in |entities_|.
   bool has_encrypted_updates_ = false;
 
   base::ThreadChecker thread_checker_;
   base::WeakPtrFactory<ModelTypeWorker> weak_ptr_factory_;
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_IMPL_MODEL_TYPE_WORKER_H_