Reland: [Sync] Record sync memory usage in histogram broken by datatypes

components/sync/syncable/directory.h

 // 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.
 
 #ifndef COMPONENTS_SYNC_SYNCABLE_DIRECTORY_H_
 #define COMPONENTS_SYNC_SYNCABLE_DIRECTORY_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 274 matching lines @@
   void SetDownloadProgress(ModelType type,
                            const sync_pb::DataTypeProgressMarker& value);
   bool HasEmptyDownloadProgress(ModelType type) const;
 
   // Gets the total number of entries in the directory.
   size_t GetEntriesCount() const;
 
   // Adds memory statistics to |pmd| for chrome://tracing.
   void OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd);
 
+  // Estimates memory usage of entries and corresponding indices of type
+  // |model_type|.
+  size_t EstimateMemoryUsageByType(ModelType model_type);
+
   // Gets/Increments transaction version of a model type. Must be called when
   // holding kernel mutex.
   int64_t GetTransactionVersion(ModelType type) const;
   void IncrementTransactionVersion(ModelType type);
 
   // Getter/setters for the per datatype context.
   void GetDataTypeContext(BaseTransaction* trans,
                           ModelType type,
                           sync_pb::DataTypeContext* context) const;
   void SetDataTypeContext(BaseWriteTransaction* trans,
@@ skipping 363 matching lines @@
 
   base::WeakPtrFactory<Directory> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Directory);
 };
 
 }  // namespace syncable
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_SYNCABLE_DIRECTORY_H_