Adding previews information to PLM UKM

chrome/browser/page_load_metrics/observers/previews_ukm_observer.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 CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_PREVIEWS_UKM_OBSERVER_H_
+#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_PREVIEWS_UKM_OBSERVER_H_
+
+#include <stdint.h>
+
+#include "base/macros.h"
+#include "chrome/browser/page_load_metrics/page_load_metrics_observer.h"
+
+namespace content {
+class NavigationHandle;
+}
+
+namespace previews {
+
+// This enum should never be re-ordered to keep a consistent set of previews
+// when reading logs.
+enum PreviewsUKMValues {

[rkaplow, 2017/06/27 22:17:09]

it's not clear to me why you want to encode this in a bitmask. I would think it
would be better to encode as seperate boolean metrics

[RyanSturm, 2017/06/28 16:19:35]

That approach is what I initially proposed, since it seems simpler. There was
pushback on the size of the data for k previews types, where k keeps growing,
but you are more of an authority on this than anyone who wanted the bitmask.

[Bryan McQuade, 2017/06/28 16:48:18]

Yes, I'm totally supportive of switching to separate booleans if that's
recommended. Apologies for my incorrect interpretation here!

[RyanSturm, 2017/07/11 21:46:40]

Done.

+  PREVIEWS_UKM_NONE = 0,
+  PREVIEWS_UKM_CLIENT_LOFI = 1,
+  PREVIEWS_UKM_SERVER_LOFI = 1 << 1,
+  PREVIEWS_UKM_LITE_PAGE = 1 << 2,
+};
+
+// Observer responsible for appending previews information to the PLM UKM
+// report.
+class PreviewsUKMObserver : public page_load_metrics::PageLoadMetricsObserver {
+ public:
+  PreviewsUKMObserver();
+  ~PreviewsUKMObserver() override;
+
+  // page_load_metrics::PageLoadMetricsObserver:
+  ObservePolicy OnStart(content::NavigationHandle* navigation_handle,
+                        const GURL& currently_committed_url,
+                        bool started_in_foreground) override;
+  ObservePolicy OnCommit(content::NavigationHandle* navigation_handle,
+                         ukm::SourceId source_id) override;
+  ObservePolicy FlushMetricsOnAppEnterBackground(
+      const page_load_metrics::mojom::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& info) override;
+  void OnComplete(const page_load_metrics::mojom::PageLoadTiming& timing,
+                  const page_load_metrics::PageLoadExtraInfo& info) override;
+  void OnLoadedResource(const page_load_metrics::ExtraRequestCompleteInfo&
+                            extra_request_complete_info) override;
+
+ private:
+  void RecordPreviewsTypes(const page_load_metrics::PageLoadExtraInfo& info);
+
+  int previews_types_ = PREVIEWS_UKM_NONE;
+
+  DISALLOW_COPY_AND_ASSIGN(PreviewsUKMObserver);
+};
+
+}  // namespace previews
+
+#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_PREVIEWS_UKM_OBSERVER_H_