Use 64 bit shift when convert uint64_t to ByteVector

components/rappor/sample.cc

 // 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.
 
 #include "components/rappor/sample.h"
 
 #include <map>
 #include <string>
 
 #include "base/logging.h"
@@ skipping 38 matching lines @@
   sizes_[field_name] = (num_flags + 7) / 8;
 }
 
 void Sample::ExportMetrics(const std::string& secret,
                            const std::string& metric_name,
                            RapporReports* reports) const {
   for (const auto& kv : fields_) {
     uint64_t value = kv.second;
     const auto it = sizes_.find(kv.first);
     DCHECK(it != sizes_.end());
-    uint64_t size = it->second;
+    size_t size = it->second;
     ByteVector value_bytes(size);
-    for (size_t i = 0; i < size; i++) {
-      // Get the value of the i-th smallest byte and copy it to the byte vector.
-      uint64_t shift = i * 8;
-      uint64_t byte_mask = 0xff << shift;
-      value_bytes[i] = (value & byte_mask) >> shift;
-    }
+    Uint64ToByteVector(value, size, &value_bytes);
     ByteVector report_bytes = internal::GenerateReport(
         secret, parameters_, value_bytes);
 
     RapporReports::Report* report = reports->add_report();
     report->set_name_hash(metrics::HashMetricName(
         metric_name + "." + kv.first));
     report->set_bits(std::string(report_bytes.begin(), report_bytes.end()));
   }
 }
 
 }  // namespace rappor