Factor management of metrics updates into its own class.

chrome/common/page_load_metrics/page_load_metrics_util.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be

[Charlie Harrison, 2017/05/24 21:02:52]

It's kinda weird to have two page_load_metrics_util files in the tree, even if
they are under different directories. Can we rename this one?
page_load_metrics_constants could work.

[Bryan McQuade, 2017/05/25 02:30:21]

done

+// found in the LICENSE file.
+
+#ifndef CHROME_COMMON_PAGE_LOAD_METRICS_PAGE_LOAD_METRICS_UTIL_H_
+#define CHROME_COMMON_PAGE_LOAD_METRICS_PAGE_LOAD_METRICS_UTIL_H_
+
+namespace page_load_metrics {
+
+// Amount of time to delay dispatch of metrics. This allows us to batch and send
+// fewer cross-process updates, given that cross-process updates can be
+// expensive.
+const int kBufferTimerDelayMillis = 1000;
+
+}  // namespace page_load_metrics
+
+#endif  // CHROME_COMMON_PAGE_LOAD_METRICS_PAGE_LOAD_METRICS_UTIL_H_