UKM: Added support for navigation sources

components/ukm/ukm_source.cc

+// Copyright 2017 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/ukm/ukm_source.h"
+#include "components/metrics/proto/ukm/source.pb.h"
+
+namespace ukm {
+
+UkmSource::UkmSource() = default;
+
+UkmSource::~UkmSource() = default;
+
+void UkmSource::PopulateProto(Source* proto_source) {
+  proto_source->set_url(committed_url_.spec());
+
+  base::TimeDelta navigation_start_in_msec =
+      navigation_start_ - base::Time::UnixEpoch();
+  proto_source->set_navigation_time_msec(
+      navigation_start_in_msec.InMilliseconds());
+
+  proto_source->set_first_contentful_paint_msec(
+      first_contentful_paint_.InMilliseconds());
+}
+
+}  // namespace ukm