Define DiagnosticMap and a basic Diagnostic hierarchy

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 6abb50a40ef1eb39c77831e406ff33a0fb99a03e..62e13b521998ae6910391f0f138b5095d71567d3 100644
--- a/tracing/tracing/metrics/system_health/responsiveness_metric.html
+++ b/tracing/tracing/metrics/system_health/responsiveness_metric.html
@@ -127,14 +127,14 @@ tr.exportTo('tr.metrics.sh', function() {
     });
 
     values.addValue(new tr.v.NumericValue(
-        model.canonicalUrl, 'response latency', responseNumeric));
+        'response latency', responseNumeric));
     values.addValue(new tr.v.NumericValue(
-        model.canonicalUrl, 'animation throughput', throughputNumeric));
+        'animation throughput', throughputNumeric));
     values.addValue(new tr.v.NumericValue(
-        model.canonicalUrl, 'animation frameTimeDiscrepancy',
+        'animation frameTimeDiscrepancy',
         frameTimeDiscrepancyNumeric));
     values.addValue(new tr.v.NumericValue(
-        model.canonicalUrl, 'animation latency', latencyNumeric));
+        'animation latency', latencyNumeric));
   }
 
   tr.metrics.MetricRegistry.register(responsivenessMetric);