Optional <TimeDelta> since they may be non existent.

chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer_unittest.cc

Index: chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer_unittest.cc
diff --git a/chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer_unittest.cc b/chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer_unittest.cc
index 812fb06fb3a1886fe92d41cff7e8853ba5739421..483b7a1fd3096d3a4b92aaed2c78c0c36ee5fe67 100644
--- a/chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer_unittest.cc
+++ b/chrome/browser/page_load_metrics/observers/aborts_page_load_metrics_observer_unittest.cc
@@ -152,7 +152,20 @@ TEST_F(AbortsPageLoadMetricsObserverTest, NoAbortNewNavigationAfterPaint) {
   PopulateRequiredTimingFields(&timing);
   NavigateAndCommit(GURL("https://www.google.com"));
   SimulateTimingUpdate(timing);
+
+  // If the system clock is low resolution

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

Looks like you can fit more words on some of these lines. Also, can we similarly
include aborts if they occur <= first paint (like we do for backgrounds)? Seems
like similar logic applies.

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

Updated the comment formatting.

The current logic does include abort if they are <= paint for logging but this
test earlier assumed that abort will be strictly > first_paint which may not be
true. Also updated the comment to clarify this.

+  // 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://www.example.com"));
-  histogram_tester().ExpectTotalCount(
-      internal::kHistogramAbortNewNavigationBeforePaint, 0);
+
+  base::HistogramTester::CountsMap counts_map =
+      histogram_tester().GetTotalCountsForPrefix(
+          internal::kHistogramAbortNewNavigationBeforePaint);
+
+  EXPECT_TRUE(counts_map.empty() || counts_map.begin()->second == 1);
 }