Adding DRP specfic UMA for FirstContentfulPaint

chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc

Index: chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc
diff --git a/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc b/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc
index 7ef0dc15033c04b2513846e4c0dda3ca9d921b07..f797ffe27cae6686a93ed5d0293a8d0e61e29051 100644
--- a/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc
+++ b/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc
@@ -357,10 +357,42 @@ TEST_F(CorePageLoadMetricsObserverTest, RapporQuickPageLoad) {
           internal::kRapporMetricsNameCoarseTiming);
   const auto& string_it = sample_obj->string_fields.find("Domain");
   EXPECT_NE(string_it, sample_obj->string_fields.end());
   EXPECT_EQ(rappor::GetDomainAndRegistrySampleFromGURL(GURL(kDefaultTestUrl)),
             string_it->second);
 
   const auto& flag_it = sample_obj->flag_fields.find("IsSlow");
   EXPECT_NE(flag_it, sample_obj->flag_fields.end());
   EXPECT_EQ(0u, flag_it->second);
 }
+
+TEST_F(CorePageLoadMetricsObserverTest, DataReductionProxyOff) {
+  page_load_metrics::PageLoadTiming timing;
+  timing.navigation_start = base::Time::FromDoubleT(1);
+  timing.first_contentful_paint = base::TimeDelta::FromSeconds(1);
+
+  NavigateAndCommit(GURL(kDefaultTestUrl));
+  SimulateTimingUpdate(timing);
+
+  // Navigate again to force logging

[bengr, 2016/02/26 22:53:57]

Are these metrics only recorded on a subsequent navigation? Won't we miss a lot
of navigations, e.g., every single navigation session? I guess there's nothing
to be done about that in this CL.

Also, add a period to the comment.

[RyanSturm, 2016/03/01 19:36:03]

Like you said, there's nothing to be done about it in this CL.

[Charlie Harrison, 2016/03/01 19:50:43]

They will also be recorded when the browser closes or the renderer shuts down.
We just navigate in the tests due to how they are set up.

+  NavigateAndCommit(GURL(kDefaultTestUrl2));
+  histogram_tester().ExpectTotalCount(internal::kHistogramFirstContentfulPaint,
+                                      1);
+  histogram_tester().ExpectTotalCount(
+      internal::kHistogramFirstContentfulPaintDataReductionProxy, 0);
+}
+
+TEST_F(CorePageLoadMetricsObserverTest, DataReductionProxyOn) {
+  page_load_metrics::PageLoadTiming timing;
+  timing.navigation_start = base::Time::FromDoubleT(1);
+  timing.first_contentful_paint = base::TimeDelta::FromSeconds(1);
+  SetSimulateFetchViaDataReductionProxy(true);

[bengr, 2016/02/26 22:53:57]

I suggest you follow the whitespace pattern in the RapporQuickPageLoad test
above.

[RyanSturm, 2016/03/01 19:36:04]

Done.

+  NavigateAndCommit(GURL(kDefaultTestUrl));
+  SimulateTimingUpdate(timing);
+  SetSimulateFetchViaDataReductionProxy(false);
+  // Navigate again to force logging

[bengr, 2016/02/26 22:53:57]

logging -> logging.

[RyanSturm, 2016/03/01 19:36:03]

Done.

+  NavigateAndCommit(GURL(kDefaultTestUrl2));
+  histogram_tester().ExpectTotalCount(internal::kHistogramFirstContentfulPaint,
+                                      1);
+  histogram_tester().ExpectTotalCount(
+      internal::kHistogramFirstContentfulPaintDataReductionProxy, 1);
+}