Optional <TimeDelta> since they may be non existent.

chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer_unittest.cc

Index: chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer_unittest.cc
diff --git a/chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer_unittest.cc b/chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer_unittest.cc
index 6bf40fab5c8d4e28298f11ee0cb8af90fb8f8dc7..c880529749327509de5615c8350e8dab12951029 100644
--- a/chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer_unittest.cc
+++ b/chrome/browser/page_load_metrics/observers/from_gws_page_load_metrics_observer_unittest.cc
@@ -7,6 +7,7 @@
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "chrome/browser/page_load_metrics/observers/page_load_metrics_observer_test_harness.h"
+#include "components/page_load_metrics/browser/page_load_metrics_util.h"
 
 namespace {
 const char kExampleUrl[] = "http://www.example.com/";
@@ -347,13 +348,25 @@ TEST_F(FromGWSPageLoadMetricsObserverTest,
   SimulateTimingUpdate(timing);
   web_contents()->WasHidden();
 
+  // If the system clock is low resolution

[Charlie Harrison, 2016/05/19 18:20:48]

Can fit more words into comment.

[shivanisha, 2016/05/23 15:06:43]

done.

+  // PageLoadTracker's background_time_ may be < timing.first_text_paint.
+  page_load_metrics::PageLoadExtraInfo info =
+      GetPageLoadExtraInfoCommittedLoad();
+
   // Navigate again to force logging.
   NavigateAndCommit(GURL("https://www.final.com"));
-  histogram_tester().ExpectTotalCount(internal::kHistogramFromGWSFirstTextPaint,
-                                      1);
-  histogram_tester().ExpectBucketCount(
-      internal::kHistogramFromGWSFirstTextPaint,
-      timing.first_text_paint.InMilliseconds(), 1);
+
+  if (page_load_metrics::WasStartedInForegroundEventInForeground(
+          timing.first_text_paint, info)) {
+    histogram_tester().ExpectTotalCount(
+        internal::kHistogramFromGWSFirstTextPaint, 1);
+    histogram_tester().ExpectBucketCount(
+        internal::kHistogramFromGWSFirstTextPaint,
+        timing.first_text_paint.InMilliseconds(), 1);
+  } else {
+    histogram_tester().ExpectTotalCount(
+        internal::kHistogramFromGWSFirstTextPaint, 0);
+  }
 }
 
 TEST_F(FromGWSPageLoadMetricsObserverTest, UnknownNavigationBeforeCommit) {
@@ -516,9 +529,22 @@ TEST_F(FromGWSPageLoadMetricsObserverTest, NoAbortNewNavigationAfterPaint) {
   PopulateRequiredTimingFields(&timing);
   NavigateAndCommit(GURL("https://example.test"));
   SimulateTimingUpdate(timing);
+
+  // If the system clock is low resolution

[Charlie Harrison, 2016/05/19 18:20:48]

Ditto. Also can you update the explanation about the abort time being "computed
and destroyed"? I think it's okay to just say that we don't consider it an abort
if the abort time is > the paint.

[shivanisha, 2016/05/23 15:06:43]

done. Also updated in aborts*unit_test

+  // PageLoadTracker's abort time may be <= first_paint.
+  // In that case the histogram will be logged else it will not be logged. This
+  // is a case where we cannot retrieve the above navigation's abort time
+  // in the test since it will be computed and destroyed in the following
+  // NavigateAndCommit call, thus both 0 and 1 counts of histograms is
+  // considered good.
+
   NavigateAndCommit(GURL("https://example.test2"));
-  histogram_tester().ExpectTotalCount(
-      internal::kHistogramFromGWSAbortNewNavigationBeforePaint, 0);
+
+  base::HistogramTester::CountsMap counts_map =
+      histogram_tester().GetTotalCountsForPrefix(
+          internal::kHistogramFromGWSAbortNewNavigationBeforePaint);
+
+  EXPECT_TRUE(counts_map.empty() || counts_map.begin()->second == 1);
 }
 
 TEST_F(FromGWSPageLoadMetricsLoggerTest, IsGoogleSearchHostname) {