UKM: Added support for navigation sources

components/ukm/ukm_source.h

+// 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.
+
+#ifndef COMPONENTS_UKM_UKM_SOURCE_H_
+#define COMPONENTS_UKM_UKM_SOURCE_H_
+
+#include <stddef.h>
+
+#include "base/macros.h"
+#include "base/time/time.h"
+#include "url/gurl.h"
+
+namespace ukm {
+
+class Source;
+
+// Contains UKM data for a single navigation entry.
+class UkmSource {
+ public:
+  UkmSource();
+  ~UkmSource();
+
+  const GURL& committed_url() const { return committed_url_; }
+  void set_committed_url(const GURL& committed_url) {
+    committed_url_ = committed_url;
+  }
+
+  base::Time navigation_start() const { return navigation_start_; }
+  void set_navigation_start(const base::Time& navigation_start) {
+    navigation_start_ = navigation_start;
+  }
+
+  base::TimeDelta first_contentful_paint() const {
+    return first_contentful_paint_;
+  }
+  void set_first_contentful_paint(
+      const base::TimeDelta& first_contentful_paint) {

[Alexei Svitkine (slow), 2017/01/25 15:35:04]

Nit: TimeDelta is meant to be passed by value. Same with Time above.

(See their headers for comments explaining this.)

[oystein (OOO til 10th of July), 2017/01/25 18:38:05]

Done.

+    first_contentful_paint_ = first_contentful_paint;
+  }
+
+  // Serializes the members of the class into the supplied proto.
+  void PopulateProto(Source* proto_source);
+
+ private:
+  GURL committed_url_;
+  base::Time navigation_start_;
+  base::TimeDelta first_contentful_paint_;
+};

[Alexei Svitkine (slow), 2017/01/25 15:35:04]

DISALLOW_COPY_AND_ASSIGN()?

[oystein (OOO til 10th of July), 2017/01/25 18:38:05]

Done.

+
+}  // namespace ukm
+
+#endif  // COMPONENTS_UKM_UKM_SOURCE_H_