Refactor NumericBuilder to HistogramBinBoundaries.

tracing/tracing/metrics/blink/gc_metric.html

Index: tracing/tracing/metrics/blink/gc_metric.html
diff --git a/tracing/tracing/metrics/blink/gc_metric.html b/tracing/tracing/metrics/blink/gc_metric.html
index 4d933e755e45f83d1bcc09730af0bc3396db106e..b8091ac8055b742a7083d160d0b28326fb1caee4 100644
--- a/tracing/tracing/metrics/blink/gc_metric.html
+++ b/tracing/tracing/metrics/blink/gc_metric.html
@@ -44,15 +44,14 @@ tr.exportTo('tr.metrics.blink', function() {
   var percentage_biggerIsBetter =
       tr.v.Unit.byName.normalizedPercentage_biggerIsBetter;
 
-  var numericBuilder = new tr.v.NumericBuilder(
-      timeDurationInMs_smallerIsBetter, 0);
   // 0.1 steps from 0 to 20 since it is the most common range.
-  numericBuilder.addLinearBins(20, 200);
   // Exponentially increasing steps from 20 to 200.
-  numericBuilder.addExponentialBins(200, 100);
+  var CUSTOM_BOUNDARIES = tr.v.HistogramBinBoundaries.createLinear(0, 20, 200)
+    .addExponentialBins(200, 100);
 
   function createNumericForTopEventTime() {
-    var n = numericBuilder.build();
+    var n = new tr.v.Histogram(
+        timeDurationInMs_smallerIsBetter, CUSTOM_BOUNDARIES);
     n.customizeSummaryOptions({
         avg: true,
         count: true,
@@ -65,7 +64,8 @@ tr.exportTo('tr.metrics.blink', function() {
   }
 
   function createNumericForIdleTime() {
-    var n = numericBuilder.build();
+    var n = new tr.v.Histogram(
+        timeDurationInMs_smallerIsBetter, CUSTOM_BOUNDARIES);
     n.customizeSummaryOptions({
         avg: true,
         count: false,
@@ -78,12 +78,8 @@ tr.exportTo('tr.metrics.blink', function() {
     return n;
   }
 
-  var PERCENTAGE_BUILDER = tr.v.NumericBuilder.createLinear(
-      percentage_biggerIsBetter,
-      tr.b.Range.fromExplicitRange(0, 1), 20);
-
   function createPercentage(numerator, denominator) {
-    var histogram = PERCENTAGE_BUILDER.build();
+    var histogram = new tr.v.Histogram(percentage_biggerIsBetter);
     if (denominator === 0)
       histogram.add(0);
     else