Periodically remove old pending navigation entries.

components/data_use_measurement/core/data_use.cc

 // Copyright 2016 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/data_use_measurement/core/data_use.h"
 
+#include "base/time/time.h"
+
 namespace data_use_measurement {
 
-DataUse::DataUse() : total_bytes_sent_(0), total_bytes_received_(0) {}
+DataUse::DataUse()
+    : total_bytes_sent_(0),
+      total_bytes_received_(0),
+      start_time_(base::Time::Now()) {}
 
 DataUse::~DataUse() {}
 
 void DataUse::MergeFrom(const DataUse& other) {
   total_bytes_sent_ += other.total_bytes_sent_;
   total_bytes_received_ += other.total_bytes_received_;
 }
 
 }  // namespace data_use_measurement