Initial UKMPageLoadMetricsObserver

chrome/browser/page_load_metrics/observers/ukm_page_load_metrics_observer.h

+// 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.
+
+#ifndef CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_UKM_PAGE_LOAD_METRICS_OBSERVER_H_
+#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_UKM_PAGE_LOAD_METRICS_OBSERVER_H_
+
+#include "base/macros.h"
+#include "chrome/browser/page_load_metrics/page_load_metrics_observer.h"
+
+class UKMPageLoadMetricsObserver
+    : public page_load_metrics::PageLoadMetricsObserver {
+ public:
+  // Returns a UKMPageLoadMetricsObserver, or nullptr if it is not needed.
+  static std::unique_ptr<page_load_metrics::PageLoadMetricsObserver>
+  CreateIfNeeded();
+
+  UKMPageLoadMetricsObserver();
+  // page_load_metrics::PageLoadMetricsObserver implementation:
+  ObservePolicy OnStart(content::NavigationHandle* navigation_handle,
+                        const GURL& currently_committed_url,
+                        bool started_in_foreground) override;
+  ObservePolicy OnHidden(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+
+  void OnComplete(
+      const page_load_metrics::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+
+ private:
+  base::TimeTicks navigation_start_;
+
+  DISALLOW_COPY_AND_ASSIGN(UKMPageLoadMetricsObserver);
+};
+
+#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_UKM_PAGE_LOAD_METRICS_OBSERVER_H_