[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_unittest.cc

Index: chrome/browser/page_load_metrics/observers/session_restore_page_load_metrics_observer_unittest.cc
diff --git a/chrome/browser/page_load_metrics/observers/session_restore_page_load_metrics_observer_unittest.cc b/chrome/browser/page_load_metrics/observers/session_restore_page_load_metrics_observer_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..724832d4ec245095f94bf487f6862249d263f3dd
--- /dev/null
+++ b/chrome/browser/page_load_metrics/observers/session_restore_page_load_metrics_observer_unittest.cc
@@ -0,0 +1,263 @@
+// 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_page_load_metrics_observer.h"
+
+#include <memory>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/macros.h"
+#include "base/stl_util.h"
+#include "base/test/histogram_tester.h"
+#include "base/time/time.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/page_load_metrics/observers/page_load_metrics_observer_tester.h"
+#include "chrome/browser/page_load_metrics/page_load_tracker.h"
+#include "chrome/browser/resource_coordinator/tab_manager.h"
+#include "chrome/browser/sessions/session_restore.h"
+#include "chrome/browser/sessions/tab_loader.h"
+#include "chrome/common/page_load_metrics/test/page_load_metrics_test_util.h"
+#include "chrome/test/base/chrome_render_view_host_test_harness.h"
+#include "chrome/test/base/testing_profile.h"
+#include "content/public/browser/browser_url_handler.h"
+#include "content/public/browser/navigation_controller.h"
+#include "content/public/browser/web_contents.h"
+#include "content/public/test/navigation_simulator.h"
+#include "content/public/test/web_contents_tester.h"
+#include "ui/base/page_transition_types.h"
+#include "url/gurl.h"
+
+using RestoredTab = SessionRestoreDelegate::RestoredTab;
+using WebContents = content::WebContents;
+
+class SessionRestorePageLoadMetricsObserverTest
+    : public ChromeRenderViewHostTestHarness {
+ public:
+  static void RegisterObservers(page_load_metrics::PageLoadTracker* tracker) {
+    tracker->AddObserver(
+        base::MakeUnique<SessionRestorePageLoadMetricsObserver>());
+  }
+
+ protected:
+  SessionRestorePageLoadMetricsObserverTest() {}
+
+  void SetUp() override {
+    ChromeRenderViewHostTestHarness::SetUp();
+
+    // Add a default web contents.
+    AddForegroundTabWithTester();
+
+    // Create the tab manager to register its SessionRestoreObserver before
+    // session restore starts.
+    g_browser_process->GetTabManager();
+
+    PopulateFirstPaintTimings();
+  }
+
+  void TearDown() override {
+    // Must be delete tabs before calling TearDown() which cleans up all the
+    // testing environment.
+    tabs_.clear();
+    ChromeRenderViewHostTestHarness::TearDown();
+  }
+
+  // Populate first paint and first [contentful,meaningful] paint timings.
+  void PopulateFirstPaintTimings() {
+    page_load_metrics::InitPageLoadTimingForTest(&timing_);
+    timing_.navigation_start = base::Time::FromDoubleT(1);
+    // Should be large enough (e.g., >20 ms) for some tests to be able to hide
+    // foreground tabs before the first pains.
+    timing_.paint_timing->first_meaningful_paint =
+        base::TimeDelta::FromSeconds(1);
+    PopulateRequiredTimingFields(&timing_);
+  }
+
+  WebContents* AddForegroundTabWithTester() {
+    tabs_.emplace_back(CreateTestWebContents());
+    WebContents* contents = tabs_.back().get();
+    auto tester =
+        base::MakeUnique<page_load_metrics::PageLoadMetricsObserverTester>(
+            contents,
+            base::BindRepeating(
+                &SessionRestorePageLoadMetricsObserverTest::RegisterObservers));
+    testers_[contents] = std::move(tester);
+    restored_tabs_.emplace_back(contents, false /* is_active */,
+                                false /* is_app */, false /* is_pinned */);
+    NavigateAndCommit(contents, GetTestURL());
+    contents->WasShown();
+    StopLoading(contents);
+    return contents;
+  }
+
+  // Return the default tab.
+  WebContents* web_contents() { return tabs_.front().get(); }
+
+  std::vector<std::unique_ptr<WebContents>>& tabs() { return tabs_; }
+
+  void ExpectFirstPaintMetricsTotalCount(int expected_total_count) const {
+    histogram_tester_.ExpectTotalCount(
+        internal::kHistogramSessionRestoreForegroundTabFirstPaint,
+        expected_total_count);
+    histogram_tester_.ExpectTotalCount(
+        internal::kHistogramSessionRestoreForegroundTabFirstContentfulPaint,
+        expected_total_count);
+    histogram_tester_.ExpectTotalCount(
+        internal::kHistogramSessionRestoreForegroundTabFirstMeaningfulPaint,
+        expected_total_count);
+  }
+
+  void RestoreTabs() {
+    TabLoader::RestoreTabs(restored_tabs_, base::TimeTicks());
+  }
+
+  void SimulateTimingUpdateForTab(WebContents* contents) {
+    ASSERT_TRUE(base::ContainsKey(testers_, contents));
+    testers_[contents]->SimulateTimingUpdate(timing_);
+  }
+
+  void StopLoading(WebContents* contents) const {
+    contents->Stop();
+    content::WebContentsTester::For(contents)->TestSetIsLoading(false);
+  }
+
+  void NavigateAndCommit(WebContents* contents, const GURL& url) const {
+    content::NavigationSimulator::NavigateAndCommitFromDocument(
+        GetTestURL(), contents->GetMainFrame());
+  }
+
+  GURL GetTestURL() const { return GURL("https://google.com"); }
+
+  const page_load_metrics::mojom::PageLoadTiming& timing() const {
+    return timing_;
+  }
+
+  std::vector<RestoredTab>& restored_tabs() { return restored_tabs_; }
+
+ private:
+  base::HistogramTester histogram_tester_;
+
+  page_load_metrics::mojom::PageLoadTiming timing_;
+  std::vector<RestoredTab> restored_tabs_;
+  std::vector<std::unique_ptr<WebContents>> tabs_;
+  std::unordered_map<
+      WebContents*,
+      std::unique_ptr<page_load_metrics::PageLoadMetricsObserverTester>>
+      testers_;
+
+  DISALLOW_COPY_AND_ASSIGN(SessionRestorePageLoadMetricsObserverTest);
+};
+
+TEST_F(SessionRestorePageLoadMetricsObserverTest, NoMetrics) {
+  ExpectFirstPaintMetricsTotalCount(0);
+}
+
+TEST_F(SessionRestorePageLoadMetricsObserverTest,
+       FirstPaintsOutOfSessionRestore) {
+  NavigateAndCommit(web_contents(), GetTestURL());
+  ASSERT_NO_FATAL_FAILURE(SimulateTimingUpdateForTab(web_contents()));
+  ExpectFirstPaintMetricsTotalCount(0);
+}
+
+TEST_F(SessionRestorePageLoadMetricsObserverTest, RestoreSingleForegroundTab) {
+  // Restore one tab which finishes loading in foreground.
+  SessionRestore::OnWillRestoreTab(web_contents());
+  RestoreTabs();
+  NavigateAndCommit(web_contents(), GetTestURL());
+  ASSERT_NO_FATAL_FAILURE(SimulateTimingUpdateForTab(web_contents()));
+  ExpectFirstPaintMetricsTotalCount(1);
+}
+
+TEST_F(SessionRestorePageLoadMetricsObserverTest,
+       RestoreMultipleForegroundTabs) {
+  WebContents* second_contents = AddForegroundTabWithTester();
+  // Restore each tab separately.
+  std::vector<std::vector<RestoredTab>> restored_tabs_list{
+      std::vector<RestoredTab>{
+          RestoredTab(web_contents(), false, false, false)},
+      std::vector<RestoredTab>{
+          RestoredTab(second_contents, false, false, false)}};
+
+  for (size_t i = 0; i < tabs().size(); ++i) {
+    WebContents* contents = tabs()[i].get();
+    SessionRestore::OnWillRestoreTab(contents);
+    TabLoader::RestoreTabs(restored_tabs_list[i], base::TimeTicks());
+    NavigateAndCommit(contents, GetTestURL());
+    ASSERT_NO_FATAL_FAILURE(SimulateTimingUpdateForTab(contents));
+    ExpectFirstPaintMetricsTotalCount(i + 1);
+  }
+}
+
+TEST_F(SessionRestorePageLoadMetricsObserverTest, RestoreBackgroundTab) {
+  // Set the tab to background before the PageLoadMetricsObserver was created.
+  web_contents()->WasHidden();
+
+  // Load the restored tab in background.
+  SessionRestore::OnWillRestoreTab(web_contents());
+  RestoreTabs();
+  NavigateAndCommit(web_contents(), GetTestURL());
+  ASSERT_NO_FATAL_FAILURE(SimulateTimingUpdateForTab(web_contents()));
+
+  // No paint timings recorded for tabs restored in background.
+  ExpectFirstPaintMetricsTotalCount(0);
+}
+
+TEST_F(SessionRestorePageLoadMetricsObserverTest, HideTabBeforeFirstPaints) {
+  // Start loading the tab.
+  SessionRestore::OnWillRestoreTab(web_contents());
+  RestoreTabs();
+  NavigateAndCommit(web_contents(), GetTestURL());
+
+  // Hide the tab before any paints.
+  web_contents()->WasHidden();
+  ASSERT_NO_FATAL_FAILURE(SimulateTimingUpdateForTab(web_contents()));
+
+  // No paint timings recorded because tab was hidden before the first paints.
+  ExpectFirstPaintMetricsTotalCount(0);
+}
+
+TEST_F(SessionRestorePageLoadMetricsObserverTest,
+       SwitchInitialRestoredForegroundTab) {
+  // Create 2 tabs: tab 0 is foreground, tab 1 is background.
+  AddForegroundTabWithTester();
+  restored_tabs()[0].contents()->WasShown();
+  restored_tabs()[1].contents()->WasHidden();
+
+  // Restore both tabs.
+  for (size_t i = 0; i < tabs().size(); ++i)
+    SessionRestore::OnWillRestoreTab(tabs()[i].get());
+  TabLoader::RestoreTabs(restored_tabs(), base::TimeTicks());
+
+  for (size_t i = 0; i < tabs().size(); ++i)
+    NavigateAndCommit(tabs()[i].get(), GetTestURL());
+
+  // Switch to tab 1 before any paint events occur.
+  restored_tabs()[0].contents()->WasHidden();
+  restored_tabs()[1].contents()->WasShown();
+  ASSERT_NO_FATAL_FAILURE(SimulateTimingUpdateForTab(web_contents()));
+
+  // No paint timings recorded because the initial foreground tab was hidden.
+  ExpectFirstPaintMetricsTotalCount(0);
+}
+
+TEST_F(SessionRestorePageLoadMetricsObserverTest, MultipleSessionRestores) {
+  size_t number_of_session_restores = 3;
+  for (size_t i = 1; i <= number_of_session_restores; ++i) {
+    // Restore session.
+    SessionRestore::OnWillRestoreTab(web_contents());
+    RestoreTabs();
+    NavigateAndCommit(web_contents(), GetTestURL());
+    ASSERT_NO_FATAL_FAILURE(SimulateTimingUpdateForTab(web_contents()));
+
+    // Number of paint timings should match the number of session restores.
+    ExpectFirstPaintMetricsTotalCount(i);
+
+    // Clear committed URL for the next restore starts from an empty URL.
+    NavigateAndCommit(web_contents(), GURL());
+    StopLoading(web_contents());
+  }
+}