Create a trace import duration metric

tracing/tracing/metrics/tracing_metric_test.html

Index: tracing/tracing/metrics/tracing_metric_test.html
diff --git a/tracing/tracing/metrics/tracing_metric_test.html b/tracing/tracing/metrics/tracing_metric_test.html
index 2e917624773755d1fbb6e79977822529bb4f874c..7f003b145d26181cf424ed8a1b0d3c595e5ff25d 100644
--- a/tracing/tracing/metrics/tracing_metric_test.html
+++ b/tracing/tracing/metrics/tracing_metric_test.html
@@ -161,5 +161,19 @@ tr.b.unittest.testSuite(function() {
         'Average CPU overhead on all threads per memory-infra dump', 91);
   });
 
+  test('traceImportDurationMetric', function() {
+    var model = new tr.Model();
+    // We can't customize the model the normal way using
+    // test_utils.newModel(customizeModelCallback) because that callback is run
+    // before the end of the import phase, so our import duration will be
+    // overwritten.
+    model.stats.traceImportDurationMs = 10;
+
+    var histograms = new tr.v.HistogramSet();
+    tr.metrics.traceImportDurationMetric(histograms, model);
+
+    assert.equal(

[benjhayden, 2017/02/17 16:48:55]

strictEqual?

[charliea (OOO until 10-5), 2017/02/17 20:26:04]

Done.

+        histograms.getHistogramNamed('trace_import_duration').average, 10);
+  });
 });
 </script>