[Prerender] first contentful paint histograms.

chrome/browser/page_load_metrics/metrics_web_contents_observer_unittest.cc

Index: chrome/browser/page_load_metrics/metrics_web_contents_observer_unittest.cc
diff --git a/chrome/browser/page_load_metrics/metrics_web_contents_observer_unittest.cc b/chrome/browser/page_load_metrics/metrics_web_contents_observer_unittest.cc
index ee45eed251f7db03ac7562022a2bad58ab1b6282..a9d054411143fb76876a6ed721146e5017954de4 100644
--- a/chrome/browser/page_load_metrics/metrics_web_contents_observer_unittest.cc
+++ b/chrome/browser/page_load_metrics/metrics_web_contents_observer_unittest.cc
@@ -109,16 +109,9 @@ class FilteringPageLoadMetricsObserver : public PageLoadMetricsObserver {
 class TestPageLoadMetricsEmbedderInterface
     : public PageLoadMetricsEmbedderInterface {
  public:
-  TestPageLoadMetricsEmbedderInterface()
-      : is_prerendering_(false), is_ntp_(false) {}
+  TestPageLoadMetricsEmbedderInterface() : is_ntp_(false) {}
 
-  bool IsPrerendering(content::WebContents* web_contents) override {
-    return is_prerendering_;
-  }
   bool IsNewTabPageUrl(const GURL& url) override { return is_ntp_; }
-  void set_is_prerendering(bool is_prerendering) {
-    is_prerendering_ = is_prerendering;
-  }
   void set_is_ntp(bool is_ntp) { is_ntp_ = is_ntp; }
   void RegisterObservers(PageLoadTracker* tracker) override {
     tracker->AddObserver(base::MakeUnique<TestPageLoadMetricsObserver>(
@@ -148,7 +141,6 @@ class TestPageLoadMetricsEmbedderInterface
   std::vector<PageLoadTiming> complete_timings_;
   std::vector<GURL> observed_committed_urls_;
   std::vector<GURL> completed_filtered_urls_;
-  bool is_prerendering_;
   bool is_ntp_;
 };
 
@@ -322,23 +314,6 @@ TEST_F(MetricsWebContentsObserverTest, SamePageNoTrigger) {
   CheckNoErrorEvents();
 }
 
-TEST_F(MetricsWebContentsObserverTest, DontLogPrerender) {

[Charlie Harrison, 2016/11/23 18:25:46]

Do you think we could maintain a test like this (maybe as a browsertest), to
ensure we aren't logging metrics for our core metrics during prerender?

[mattcary, 2016/11/24 09:07:42]

Sorry, dropped this. I started looking in, it's a little tricky, especially
since the prerender browsertests need to be done over in a different directory.
I could have a test that spot-checks some of the core metrics, but I think it
would be difficult to guarantee coverage without some explicit registry scheme.
Would that be enough?

[mattcary, 2016/11/24 13:43:47]

Done.

[Charlie Harrison, 2016/12/22 19:51:25]

Sorry I missed this. I would be happy to test just a single critical metric like
NavigationToFirstContentfulPaint. I think it would be fine for prerender
browsertests to check this, or you could e.g. have a test which has <link
rel='prerender'> in it.

-  PageLoadTiming timing;
-  timing.navigation_start = base::Time::FromDoubleT(1);
-
-  content::WebContentsTester* web_contents_tester =
-      content::WebContentsTester::For(web_contents());
-  embedder_interface_->set_is_prerendering(true);
-  observer_->WasHidden();
-
-  web_contents_tester->NavigateAndCommit(GURL(kDefaultTestUrl));
-  SimulateTimingUpdate(timing);
-  web_contents_tester->NavigateAndCommit(GURL(kDefaultTestUrl2));
-  ASSERT_EQ(0, CountUpdatedTimingReported());
-  ASSERT_EQ(0, CountCompleteTimingReported());
-  CheckNoErrorEvents();
-}
-
 TEST_F(MetricsWebContentsObserverTest, DontLogNewTabPage) {
   PageLoadTiming timing;
   timing.navigation_start = base::Time::FromDoubleT(1);