[tracing] Move math utilities from base into their own subdirectory (attempt 2)

tracing/tracing/metrics/system_health/responsiveness_metric.html

Index: tracing/tracing/metrics/system_health/responsiveness_metric.html
diff --git a/tracing/tracing/metrics/system_health/responsiveness_metric.html b/tracing/tracing/metrics/system_health/responsiveness_metric.html
index e1a4ab39ae04e204881f6929a74c0f7466e98519..89309cc771c8cc57809826b3f16cc49abdac5ace 100644
--- a/tracing/tracing/metrics/system_health/responsiveness_metric.html
+++ b/tracing/tracing/metrics/system_health/responsiveness_metric.html
@@ -5,7 +5,7 @@ Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 -->
 
-<link rel="import" href="/tracing/base/statistics.html">
+<link rel="import" href="/tracing/base/math/statistics.html">
 <link rel="import" href="/tracing/metrics/metric_registry.html">
 <link rel="import" href="/tracing/metrics/system_health/utils.html">
 <link rel="import" href="/tracing/model/user_model/animation_expectation.html">
@@ -51,7 +51,8 @@ tr.exportTo('tr.metrics.sh', function() {
     });
 
     var absolute = true;
-    return tr.b.Statistics.timestampsDiscrepancy(frameTimestamps, absolute);
+    return tr.b.math.Statistics.timestampsDiscrepancy(
+        frameTimestamps, absolute);
   }
 
   /**