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

chrome/browser/page_load_metrics/observers/session_restore_page_load_metrics_observer.h

Index: chrome/browser/page_load_metrics/observers/session_restore_page_load_metrics_observer.h
diff --git a/chrome/browser/page_load_metrics/observers/session_restore_page_load_metrics_observer.h b/chrome/browser/page_load_metrics/observers/session_restore_page_load_metrics_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..f8c5011846fe0b3246cf339961382fa0ffc1f34e
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+++ b/chrome/browser/page_load_metrics/observers/session_restore_page_load_metrics_observer.h
@@ -0,0 +1,45 @@
+// 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_PAGE_LOAD_METRICS_OBSERVER_H_
+#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_SESSION_RESTORE_PAGE_LOAD_METRICS_OBSERVER_H_
+
+#include "base/macros.h"
+#include "chrome/browser/page_load_metrics/page_load_metrics_observer.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. This
+// observer observes foreground tabs created by session restores only. It will
+// stop observing if the tab gets hidden, reloaded, or navigated away.
+class SessionRestorePageLoadMetricsObserver
+    : public page_load_metrics::PageLoadMetricsObserver {
+ public:
+  SessionRestorePageLoadMetricsObserver();
+
+  // page_load_metrics::PageLoadMetricsObserver:
+  ObservePolicy OnStart(content::NavigationHandle* navigation_handle,
+                        const GURL& currently_committed_url,
+                        bool started_in_foreground) 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:
+  DISALLOW_COPY_AND_ASSIGN(SessionRestorePageLoadMetricsObserver);
+};
+
+#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_SESSION_RESTORE_PAGE_LOAD_METRICS_OBSERVER_H_