[Prerender] first contentful paint histograms.

chrome/browser/prerender/prerender_browsertest.cc

Index: chrome/browser/prerender/prerender_browsertest.cc
diff --git a/chrome/browser/prerender/prerender_browsertest.cc b/chrome/browser/prerender/prerender_browsertest.cc
index 8f4dbe09173d4ee5dfa386001409ccfb2fc73f57..397ea294179dd6651c760f99120947d489fb11a6 100644
--- a/chrome/browser/prerender/prerender_browsertest.cc
+++ b/chrome/browser/prerender/prerender_browsertest.cc
@@ -26,6 +26,7 @@
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/scoped_feature_list.h"
+#include "base/test/simple_test_tick_clock.h"
 #include "base/test/test_timeouts.h"
 #include "base/values.h"
 #include "build/build_config.h"
@@ -40,6 +41,8 @@
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/browser/external_protocol/external_protocol_handler.h"
 #include "chrome/browser/net/prediction_options.h"
+#include "chrome/browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.h"
+#include "chrome/browser/page_load_metrics/observers/prerender_page_load_metrics_observer.h"
 #include "chrome/browser/password_manager/password_store_factory.h"
 #include "chrome/browser/predictors/autocomplete_action_predictor.h"
 #include "chrome/browser/predictors/autocomplete_action_predictor_factory.h"
@@ -780,6 +783,8 @@ class PrerenderBrowserTest : public test_utils::PrerenderInProcessBrowserTest {
     call_javascript_ = false;
   }
 
+  void EnableJavascriptCalls() { call_javascript_ = true; }
+
   void DisableLoadEventCheck() {
     check_load_events_ = false;
   }
@@ -934,6 +939,26 @@ class PrerenderBrowserTest : public test_utils::PrerenderInProcessBrowserTest {
         base::ASCIIToUTF16(javascript));
   }
 
+  base::SimpleTestTickClock* OverridePrerenderManagerTimeTicks() {
+    auto clock = base::MakeUnique<base::SimpleTestTickClock>();
+    auto clock_ptr = clock.get();
+    // The default zero time causes the prerender manager to do strange things.
+    clock->Advance(base::TimeDelta::FromSeconds(1));
+    GetPrerenderManager()->SetTickClockForTesting(std::move(clock));
+    return clock_ptr;
+  }
+
+  void SetMidLoadClockAdvance(base::SimpleTestTickClock* clock,
+                              base::TimeDelta delta) {
+    mid_load_clock_ = clock;
+    mid_load_clock_tick_advance_ = delta;
+  }
+
+  void ClearMidLoadClock() {
+    mid_load_clock_tick_advance_ = base::TimeDelta();
+    mid_load_clock_ = nullptr;
+  }
+
  private:
   // TODO(davidben): Remove this altogether so the tests don't globally assume
   // only one prerender.
@@ -958,6 +983,11 @@ class PrerenderBrowserTest : public test_utils::PrerenderInProcessBrowserTest {
         NavigateWithPrerenders(loader_url, expected_final_status_queue);
     prerenders[0]->WaitForLoads(expected_number_of_loads);
 
+    if (!mid_load_clock_tick_advance_.is_zero()) {
+      EXPECT_TRUE(mid_load_clock_);
+      mid_load_clock_->Advance(mid_load_clock_tick_advance_);
+    }
+
     FinalStatus expected_final_status = expected_final_status_queue.front();
     if (ShouldAbortPrerenderBeforeSwap(expected_final_status)) {
       // The prerender will abort on its own. Assert it does so correctly.
@@ -1050,12 +1080,17 @@ class PrerenderBrowserTest : public test_utils::PrerenderInProcessBrowserTest {
   std::string loader_path_;
   std::string loader_query_;
   base::test::ScopedFeatureList feature_list_;
+  base::TimeDelta mid_load_clock_tick_advance_;
+  base::SimpleTestTickClock* mid_load_clock_;
 };
 
 // Checks that a page is correctly prerendered in the case of a
 // <link rel=prerender> tag and then loaded into a tab in response to a
 // navigation.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderPage) {
+  test_utils::FirstContentfulPaintManagerWaiter* fcp_waiter =
+      test_utils::FirstContentfulPaintManagerWaiter::Create(
+          GetPrerenderManager());
   PrerenderTestURL("/prerender/prerender_page.html", FINAL_STATUS_USED, 1);
   EXPECT_EQ(1, GetPrerenderDomContentLoadedEventCountForLinkNumber(0));
   histogram_tester().ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
@@ -1070,18 +1105,25 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderPage) {
       GetActiveWebContents()->GetRenderProcessHost());
   NavigateToDestURL();
   channel_close_watcher.WaitForChannelClose();
+  fcp_waiter->Wait();
 
   histogram_tester().ExpectTotalCount("Prerender.websame_PerceivedPLT", 1);
   histogram_tester().ExpectTotalCount("Prerender.websame_PerceivedPLTMatched",
                                       1);
   histogram_tester().ExpectTotalCount(
       "Prerender.websame_PerceivedPLTMatchedComplete", 1);
+  histogram_tester().ExpectTotalCount("Prerender.websame_PerceivedTTFCP", 1);
+  histogram_tester().ExpectTotalCount(
+      "Prerender.websame_PerceivedTTFCPRecorded", 1);
 
   ASSERT_TRUE(IsEmptyPrerenderLinkManager());
 }
 
 // Checks that cross-domain prerenders emit the correct histograms.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderPageCrossDomain) {
+  test_utils::FirstContentfulPaintManagerWaiter* fcp_waiter =
+      test_utils::FirstContentfulPaintManagerWaiter::Create(
+          GetPrerenderManager());
   PrerenderTestURL(GetCrossDomainTestUrl("prerender/prerender_page.html"),
                    FINAL_STATUS_USED, 1);
   histogram_tester().ExpectTotalCount("Prerender.none_PerceivedPLT", 1);
@@ -1092,11 +1134,14 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderPageCrossDomain) {
       "Prerender.webcross_PrerenderNotSwappedInPLT", 1);
 
   NavigateToDestURL();
+  fcp_waiter->Wait();
+
   histogram_tester().ExpectTotalCount("Prerender.webcross_PerceivedPLT", 1);
   histogram_tester().ExpectTotalCount("Prerender.webcross_PerceivedPLTMatched",
                                       1);
   histogram_tester().ExpectTotalCount(
       "Prerender.webcross_PerceivedPLTMatchedComplete", 1);
+  histogram_tester().ExpectTotalCount("Prerender.webcross_PerceivedTTFCP", 1);
 }
 
 // Checks that pending prerenders launch and receive proper event treatment.
@@ -3258,6 +3303,197 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, AutosigninInPrerenderer) {
   EXPECT_EQ(0, done_counter.count());
 }
 
+IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, FirstContentfulPaintTimingSimple) {

[Bryan McQuade, 2016/11/18 14:52:37]

looking at these tests, they don't feel like browser/end to end tests as much as
unit tests of the PrerenderPageLoadMetricsObserver. But you end up having to
bring up a lot of machinery just to unit test this class. Is it possible to
instead add a prerender_page_load_metrics_observer_unittest and use the existing
PageLoadMetricsObserverTestHarness to write these same tests?

[mattcary, 2016/11/18 15:14:14]

As mentioned in the other comment, no, apparently it isn't possible. I tried
very hard.

+  GetPrerenderManager()->DisablePageLoadMetricsObserverForTesting();
+  base::SimpleTestTickClock* clock = OverridePrerenderManagerTimeTicks();
+  PrerenderTestURL("/prerender/prerender_page.html", FINAL_STATUS_USED, 1);
+  clock->Advance(base::TimeDelta::FromSeconds(1));
+  NavigateToDestURL();
+  PrerenderPageLoadMetricsObserver observer(GetPrerenderManager(),
+                                            GetActiveWebContents());
+
+  page_load_metrics::PageLoadTiming timing;
+  timing.navigation_start = base::Time::FromDoubleT(1);
+  timing.first_contentful_paint = base::TimeDelta::FromMilliseconds(2654);
+  page_load_metrics::PageLoadMetricsObserverTestHarness::
+      PopulateRequiredTimingFields(&timing);
+  observer.OnFirstContentfulPaint(
+      timing,
+      page_load_metrics::PageLoadExtraInfo(
+          base::TimeDelta(), base::TimeDelta(), false, false, dest_url(),
+          dest_url(), page_load_metrics::ABORT_NONE, false, base::TimeDelta(),
+          0, 0, page_load_metrics::PageLoadMetadata()));
+
+  histogram_tester().ExpectTotalCount("Prerender.websame_PerceivedTTFCP", 1);
+  histogram_tester().ExpectUniqueSample("Prerender.websame_PerceivedTTFCP",
+                                        1654, 1);
+}
+
+IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, FirstContentfulPaintTimingReuse) {
+  GetPrerenderManager()->DisablePageLoadMetricsObserverForTesting();
+  base::SimpleTestTickClock* clock = OverridePrerenderManagerTimeTicks();
+
+  GURL url = embedded_test_server()->GetURL("/prerender/prerender_page.html");
+  DisableJavascriptCalls();
+  PrerenderTestURL(url, FINAL_STATUS_CANCELLED, 0);
+
+  // This prerender cancels and reuses the first.
+  clock->Advance(base::TimeDelta::FromSeconds(1));
+  EnableJavascriptCalls();
+  PrerenderTestURL(url, FINAL_STATUS_USED, 1);
+  clock->Advance(base::TimeDelta::FromSeconds(1));
+  NavigateToDestURL();
+
+  PrerenderPageLoadMetricsObserver observer(GetPrerenderManager(),
+                                            GetActiveWebContents());
+
+  page_load_metrics::PageLoadTiming timing;
+  timing.navigation_start = base::Time::FromDoubleT(1);
+  timing.first_contentful_paint = base::TimeDelta::FromMilliseconds(2361);
+  page_load_metrics::PageLoadMetricsObserverTestHarness::
+      PopulateRequiredTimingFields(&timing);
+  observer.OnFirstContentfulPaint(
+      timing,
+      page_load_metrics::PageLoadExtraInfo(
+          base::TimeDelta(), base::TimeDelta(), false, false, dest_url(),
+          dest_url(), page_load_metrics::ABORT_NONE, false, base::TimeDelta(),
+          0, 0, page_load_metrics::PageLoadMetadata()));
+
+  histogram_tester().ExpectTotalCount("Prerender.websame_PerceivedTTFCP", 1);
+  // If the first prerender had been used, the perceived TTFCP would have been
+  // under a second: 2362ms - 2 sec worth of Advance().
+  histogram_tester().ExpectUniqueSample("Prerender.websame_PerceivedTTFCP",
+                                        1361, 1);
+}
+
+IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
+                       FirstContentfulPaintTimingTimeout) {
+  GetPrerenderManager()->DisablePageLoadMetricsObserverForTesting();
+  base::SimpleTestTickClock* clock = OverridePrerenderManagerTimeTicks();
+
+  // Make the first prerender time out.
+  SetMidLoadClockAdvance(clock, GetPrerenderManager()->config().time_to_live +
+                                    base::TimeDelta::FromSeconds(10));
+
+  GURL url = embedded_test_server()->GetURL("/prerender/prerender_page.html");
+  PrerenderTestURL(url, FINAL_STATUS_TIMED_OUT, 1);
+
+  ClearMidLoadClock();
+  PrerenderTestURL(url, FINAL_STATUS_USED, 1);
+  clock->Advance(base::TimeDelta::FromSeconds(1));
+  NavigateToDestURL();
+
+  PrerenderPageLoadMetricsObserver observer(GetPrerenderManager(),
+                                            GetActiveWebContents());
+
+  page_load_metrics::PageLoadTiming timing;
+  timing.navigation_start = base::Time::FromDoubleT(1);
+  timing.first_contentful_paint = base::TimeDelta::FromMilliseconds(2361);
+  page_load_metrics::PageLoadMetricsObserverTestHarness::
+      PopulateRequiredTimingFields(&timing);
+  observer.OnFirstContentfulPaint(
+      timing,
+      page_load_metrics::PageLoadExtraInfo(
+          base::TimeDelta(), base::TimeDelta(), false, false, dest_url(),
+          dest_url(), page_load_metrics::ABORT_NONE, false, base::TimeDelta(),
+          0, 0, page_load_metrics::PageLoadMetadata()));
+
+  histogram_tester().ExpectTotalCount("Prerender.websame_PerceivedTTFCP", 1);
+  // If the timed out had been used, the perceived TTFCP would have been
+  // negative.
+  histogram_tester().ExpectUniqueSample("Prerender.websame_PerceivedTTFCP",
+                                        1361, 1);
+}
+
+IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
+                       FirstContentfulPaintTimingNoCommit) {
+  GetPrerenderManager()->DisablePageLoadMetricsObserverForTesting();
+  base::SimpleTestTickClock* clock = OverridePrerenderManagerTimeTicks();
+
+  GURL url = embedded_test_server()->GetURL("/prerender/prerender_page.html");
+  base::FilePath url_file = ui_test_utils::GetTestFilePath(
+      base::FilePath(),
+      base::FilePath(FILE_PATH_LITERAL("prerender/prerender_page.html")));
+
+  base::RunLoop prerender_start_loop;
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&CreateHangingFirstRequestInterceptorOnIO, url, url_file,
+                 prerender_start_loop.QuitClosure()));
+  DisableJavascriptCalls();
+  PrerenderTestURL(url, FINAL_STATUS_NAVIGATION_UNCOMMITTED, 0);
+  prerender_start_loop.Run();
+
+  clock->Advance(base::TimeDelta::FromSeconds(1));
+
+  NavigateToDestURLWithDisposition(WindowOpenDisposition::CURRENT_TAB, false);
+
+  PrerenderPageLoadMetricsObserver observer(GetPrerenderManager(),
+                                            GetActiveWebContents());
+
+  page_load_metrics::PageLoadTiming timing;
+  timing.navigation_start = base::Time::FromDoubleT(1);
+  timing.first_contentful_paint = base::TimeDelta::FromMilliseconds(2362);
+  page_load_metrics::PageLoadMetricsObserverTestHarness::
+      PopulateRequiredTimingFields(&timing);
+  observer.OnFirstContentfulPaint(
+      timing,
+      page_load_metrics::PageLoadExtraInfo(
+          base::TimeDelta(), base::TimeDelta(), false, false, dest_url(),
+          dest_url(), page_load_metrics::ABORT_NONE, false, base::TimeDelta(),
+          0, 0, page_load_metrics::PageLoadMetadata()));
+
+  histogram_tester().ExpectTotalCount("Prerender.none_PerceivedTTFCP", 0);
+  histogram_tester().ExpectTotalCount("Prerender.none_PerceivedTTFCPRecorded",
+                                      1);
+
+  // Check that the prerender didn't happen with a defined origin.
+  histogram_tester().ExpectTotalCount("Prerender.websame_PerceivedTTFCP", 0);
+  histogram_tester().ExpectTotalCount(
+      "Prerender.websame_PerceivedTTFCPRecorded", 0);
+
+  // A FCP is fired by the observer, but the manager should detect that the
+  // perceived time is not set and so update the following histogram.
+  histogram_tester().ExpectUniqueSample("Prerender.none_PerceivedTTFCPRecorded",
+                                        0, 1);
+}
+
+IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
+                       FirstContentfulPaintTimingTwoPages) {
+  GetPrerenderManager()->DisablePageLoadMetricsObserverForTesting();
+  base::SimpleTestTickClock* clock = OverridePrerenderManagerTimeTicks();
+
+  DisableJavascriptCalls();
+  // First prerender a different page from the usual target.
+  PrerenderTestURL("/prerender/prefetch_page.html", FINAL_STATUS_CANCELLED, 0);
+
+  clock->Advance(base::TimeDelta::FromSeconds(1));
+  EnableJavascriptCalls();
+  PrerenderTestURL("/prerender/prerender_page.html", FINAL_STATUS_USED, 1);
+
+  clock->Advance(base::TimeDelta::FromSeconds(1));
+  NavigateToDestURL();
+
+  PrerenderPageLoadMetricsObserver observer(GetPrerenderManager(),
+                                            GetActiveWebContents());
+  page_load_metrics::PageLoadTiming timing;
+  timing.navigation_start = base::Time::FromDoubleT(1);
+  // The FCP time should end up on the edge of the bucket.
+  timing.first_contentful_paint = base::TimeDelta::FromMilliseconds(2654);
+  page_load_metrics::PageLoadMetricsObserverTestHarness::
+      PopulateRequiredTimingFields(&timing);
+  observer.OnFirstContentfulPaint(
+      timing,
+      page_load_metrics::PageLoadExtraInfo(
+          base::TimeDelta(), base::TimeDelta(), false, false, dest_url(),
+          dest_url(), page_load_metrics::ABORT_NONE, false, base::TimeDelta(),
+          0, 0, page_load_metrics::PageLoadMetadata()));
+
+  histogram_tester().ExpectTotalCount("Prerender.websame_PerceivedTTFCP", 1);
+  histogram_tester().ExpectUniqueSample("Prerender.websame_PerceivedTTFCP",
+                                        1654, 1);
+}
+
 class PrerenderIncognitoBrowserTest : public PrerenderBrowserTest {
  public:
   void SetUpOnMainThread() override {