Measuring data use of different ModelTypes in Sync Service.

net/url_request/data_use_measurement.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 NET_URL_REQUEST_DATA_USE_MEASUREMENT_H_
 #define NET_URL_REQUEST_DATA_USE_MEASUREMENT_H_
 
 namespace net {
 class URLFetcher;
 }  // namespace net
 
 // Records the data use of |service_name| based on the information included in
 // fetcher. Normally used for recording data use of services using URLFetcher.
 // After extracting necessary data, such as message size in different
 // directions, calls the function to record use in DataUse.Services.{Dimensions}
 // and DataUse.Service.|service_name| histograms.
 void DataUseReport(const std::string& service_name,
                    const net::URLFetcher* fetcher);
 
+void SparseDataUseReport(const std::string& histogram_name,
+                         int value,
+                         int count);
+
 #endif  // NET_URL_REQUEST_DATA_USE_MEASUREMENT_H_