[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..35cc3bd62b86eb8d5e9b059839fd1ecbd4569006
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/session_restore_foreground_tab_page_load_metrics_observer.h
@@ -0,0 +1,60 @@
+// 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 <memory>
+
+#include "chrome/browser/page_load_metrics/page_load_metrics_observer.h"
+#include "chrome/browser/resource_coordinator/tab_manager.h"
+
+namespace internal {
+
+extern const char kHistogramSessionRestoreForegroundTabFirstPaint[];
+extern const char kHistogramSessionRestoreForegroundTabFirstContentfulPaint[];
+extern const char kHistogramSessionRestoreForegroundTabFirstMeaningfulPaint[];
+
+}  // namespace internal
+
+// Record page load metrics of foreground tabs during session restore.
+class SessionRestoreForegroundTabPageLoadMetricsObserver

[lpy, 2017/06/27 19:57:55]

SessionRestorePageLoadMetricsObserver

[fmeawad, 2017/06/27 20:26:09]

+1

[ducbui, 2017/06/27 21:04:13]

Done.

[ducbui, 2017/06/27 21:19:22]

I also removed the DCHECK() because if we are not on TabManager-supported
platforms, this function will return false.

+    : public page_load_metrics::PageLoadMetricsObserver {
+ public:
+  SessionRestoreForegroundTabPageLoadMetricsObserver() {}
+
+  static std::unique_ptr<SessionRestoreForegroundTabPageLoadMetricsObserver>
+  CreateIfNeeded();
+
+  // PageLoadMetricsObserver implementation:
+  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:
+  static resource_coordinator::TabManager* GetTabManager();

[lpy, 2017/06/27 19:57:55]

Why do we need this method instead of inlining into call site?

[ducbui, 2017/06/27 21:04:13]

Acknowledged. I am fine with your comment which makes the code shorter. I wrote
those functions to clarify my intentions, but they seems unnecessary here.

+
+  static bool HasInitialForegroundTabChanged();
+
+  static bool IsSessionRestoreLoadingTabs();
+
+  DISALLOW_COPY_AND_ASSIGN(SessionRestoreForegroundTabPageLoadMetricsObserver);
+};
+#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_SESSION_RESTORE_FOREGROUND_TAB_PAGE_LOAD_METRICS_OBSERVER_H_