[Tab Metrics] Measure FP, FCP and FMP for Foreground Tab during Session Restore

chrome/browser/page_load_metrics/observers/session_restore_foreground_tab_page_load_metrics_observer.h

Index: chrome/browser/page_load_metrics/observers/session_restore_foreground_tab_page_load_metrics_observer.h
diff --git a/chrome/browser/page_load_metrics/observers/session_restore_foreground_tab_page_load_metrics_observer.h b/chrome/browser/page_load_metrics/observers/session_restore_foreground_tab_page_load_metrics_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..0c4fd57eb2e2aa0926340ea3be29d9f257dfd56e
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/session_restore_foreground_tab_page_load_metrics_observer.h
@@ -0,0 +1,40 @@
+// 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_SESSION_RESTORE_FOREGROUND_TAB_PAGE_LOAD_METRICS_OBSERVER_H_
+#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_SESSION_RESTORE_FOREGROUND_TAB_PAGE_LOAD_METRICS_OBSERVER_H_
+
+#include "chrome/browser/page_load_metrics/page_load_metrics_observer.h"
+
+// Record page load metrics for foreground tabs during session restore
+// This does not track tabs that are foreground at start but then backgrounded
+// We will still get metrics for a tab which becomes foreground before
+// it started

[fmeawad, 2017/06/09 21:02:54]

This comment is confusing, I would simplify it to the first line only.

[ducbui, 2017/06/10 00:40:16]

Done.

+class SessionRestoreForegroundTabPageLoadMetricsObserver

[fmeawad, 2017/06/09 21:02:54]

I think the observer should be for all situations regarding the session restore,
it does not make sense that we would have an observer for foreground tab and
another for background tab. Maybe add a method like: isForegroundTab similar to
isDuringSessionRestore

[ducbui, 2017/06/10 00:40:16]

I changed the class name into a more general one
SessionRestorePageLoadMetricsObserver and revised its methods accordingly.

+    : public page_load_metrics::PageLoadMetricsObserver {
+ public:
+  ObservePolicy OnStart(content::NavigationHandle* navigation_handle,
+                        const GURL& currently_committed_url,
+                        bool started_in_foreground) override;
+
+  ObservePolicy OnHidden(
+      const page_load_metrics::mojom::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& info) override;
+
+  void OnFirstPaintInPage(
+      const page_load_metrics::mojom::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+
+  void OnFirstContentfulPaintInPage(
+      const page_load_metrics::mojom::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+
+  void OnFirstMeaningfulPaintInMainFrameDocument(
+      const page_load_metrics::mojom::PageLoadTiming& timing,
+      const page_load_metrics::PageLoadExtraInfo& extra_info) override;
+
+ private:
+  bool IsDuringSessionRestore() const;
+};
+#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_SESSION_RESTORE_FOREGROUND_TAB_PAGE_LOAD_METRICS_OBSERVER_H_