[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.cc

Index: chrome/browser/page_load_metrics/observers/session_restore_foreground_tab_page_load_metrics_observer.cc
diff --git a/chrome/browser/page_load_metrics/observers/session_restore_foreground_tab_page_load_metrics_observer.cc b/chrome/browser/page_load_metrics/observers/session_restore_foreground_tab_page_load_metrics_observer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..194e313e26adb6dd97b51c81ef59687ab7640670
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/session_restore_foreground_tab_page_load_metrics_observer.cc
@@ -0,0 +1,92 @@
+// 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.
+
+#include "chrome/browser/page_load_metrics/observers/session_restore_foreground_tab_page_load_metrics_observer.h"
+
+#include "base/metrics/histogram_macros.h"
+#include "chrome/browser/browser_process.h"
+
+namespace internal {
+
+const char kHistogramSessionRestoreForegroundTabFirstPaint[] =
+    "TabManager.Experimental.SessionRestore.ForegroundTab.FirstPaint";
+const char kHistogramSessionRestoreForegroundTabFirstContentfulPaint[] =
+    "TabManager.Experimental.SessionRestore.ForegroundTab.FirstContentfulPaint";
+const char kHistogramSessionRestoreForegroundTabFirstMeaningfulPaint[] =
+    "TabManager.Experimental.SessionRestore.ForegroundTab.FirstMeaningfulPaint";
+
+}  // namespace internal
+
+// static
+std::unique_ptr<SessionRestoreForegroundTabPageLoadMetricsObserver>
+SessionRestoreForegroundTabPageLoadMetricsObserver::CreateIfNeeded() {
+  return GetTabManager() && IsSessionRestoreLoadingTabs() &&
+                 !HasInitialForegroundTabChanged()
+             ? base::MakeUnique<
+                   SessionRestoreForegroundTabPageLoadMetricsObserver>()
+             : nullptr;
+}
+
+page_load_metrics::PageLoadMetricsObserver::ObservePolicy
+SessionRestoreForegroundTabPageLoadMetricsObserver::OnStart(
+    content::NavigationHandle* navigation_handle,
+    const GURL& currently_committed_url,
+    bool started_in_foreground) {
+  return started_in_foreground ? CONTINUE_OBSERVING : STOP_OBSERVING;
+}
+
+page_load_metrics::PageLoadMetricsObserver::ObservePolicy
+SessionRestoreForegroundTabPageLoadMetricsObserver::OnHidden(
+    const page_load_metrics::mojom::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& info) {
+  return STOP_OBSERVING;
+}
+
+void SessionRestoreForegroundTabPageLoadMetricsObserver::OnFirstPaintInPage(
+    const page_load_metrics::mojom::PageLoadTiming& timing,
+    const page_load_metrics::PageLoadExtraInfo& extra_info) {
+  UMA_HISTOGRAM_TIMES(internal::kHistogramSessionRestoreForegroundTabFirstPaint,
+                      timing.paint_timing->first_paint.value());
+}
+
+void SessionRestoreForegroundTabPageLoadMetricsObserver::
+    OnFirstContentfulPaintInPage(
+        const page_load_metrics::mojom::PageLoadTiming& timing,
+        const page_load_metrics::PageLoadExtraInfo& extra_info) {
+  UMA_HISTOGRAM_TIMES(
+      internal::kHistogramSessionRestoreForegroundTabFirstContentfulPaint,
+      timing.paint_timing->first_contentful_paint.value());
+}
+
+void SessionRestoreForegroundTabPageLoadMetricsObserver::
+    OnFirstMeaningfulPaintInMainFrameDocument(
+        const page_load_metrics::mojom::PageLoadTiming& timing,
+        const page_load_metrics::PageLoadExtraInfo& extra_info) {
+  UMA_HISTOGRAM_TIMES(
+      internal::kHistogramSessionRestoreForegroundTabFirstMeaningfulPaint,
+      timing.paint_timing->first_meaningful_paint.value());
+}
+
+// static
+resource_coordinator::TabManager*
+SessionRestoreForegroundTabPageLoadMetricsObserver::GetTabManager() {
+  resource_coordinator::TabManager* tab_manager =
+      g_browser_process->GetTabManager();
+  // tab_manager should not be null because this is used only
+  // on TabManager-supported platforms
+  DCHECK(tab_manager);
+  return tab_manager;
+}
+
+// static
+bool SessionRestoreForegroundTabPageLoadMetricsObserver::
+    HasInitialForegroundTabChanged() {
+  return GetTabManager()->HasSessionRestoreInitialForegroundTabChanged();
+}
+
+// static
+bool SessionRestoreForegroundTabPageLoadMetricsObserver::
+    IsSessionRestoreLoadingTabs() {
+  return GetTabManager()->IsSessionRestoreLoadingTabs();
+}