Migrate tracing_metric from ScalarNumeric to Histograms

tracing/tracing/metrics/tracing_metric.html

Index: tracing/tracing/metrics/tracing_metric.html
diff --git a/tracing/tracing/metrics/tracing_metric.html b/tracing/tracing/metrics/tracing_metric.html
index 525585841095388dd19062e67f0d1d4d89683e5d..792882d495e6db51390b12de4305aebe4179daf6 100644
--- a/tracing/tracing/metrics/tracing_metric.html
+++ b/tracing/tracing/metrics/tracing_metric.html
@@ -8,7 +8,7 @@ found in the LICENSE file.
 <link rel="import" href="/tracing/base/iteration_helpers.html">
 <link rel="import" href="/tracing/metrics/metric_registry.html">
 <link rel="import" href="/tracing/value/diagnostics/diagnostic_map.html">
-<link rel="import" href="/tracing/value/numeric.html">
+<link rel="import" href="/tracing/value/histogram.html">
 <link rel="import" href="/tracing/value/value.html">
 
 <script>
@@ -17,11 +17,22 @@ found in the LICENSE file.
 tr.exportTo('tr.metrics', function() {
   var MEMORY_INFRA_TRACING_CATEGORY = 'disabled-by-default-memory-infra';
 
+  var TIME_NUMERIC_BUILDER = tr.v.NumericBuilder.createExponential(
+      tr.v.Unit.byName.timeDurationInMs_smallerIsBetter,
+      tr.b.Range.fromExplicitRange(1e-2, 1e5), 30);

[Zhen Wang, 2016/08/25 21:19:46]

ssid, can you take a look to see if this setting is reasonable to you?

[ssid, 2016/08/26 22:32:13]

I think the lower could be 1e-3. IIUC, 1e-2 means 0.01.
The trace events can sometimes measure duration upto 0.001ms. Not saying these
numbers are useful to track, but just for the sake of correctness.

+
+  var BYTE_NUMERIC_BUILDER = tr.v.NumericBuilder.createExponential(
+      tr.v.Unit.byName.sizeInBytes_smallerIsBetter,
+      tr.b.Range.fromExplicitRange(1, 1e9), 30);
+
+  var COUNT_NUMERIC_BUILDER = tr.v.NumericBuilder.createLinear(
+      tr.v.Unit.byName.count_smallerIsBetter,
+      tr.b.Range.fromExplicitRange(0, 1000), 40);

[Zhen Wang, 2016/08/25 21:19:46]

1000 is not enough, e.g, the following has close to 70,000. I would suggest
using at least 100,000 as the upper bound.
https://chromeperf.appspot.com/report?sid=927f8f18a8a6e7747c4c4a2d63980e257c2...

And why are there 40 bins and the other 2 are 30 bins?

[benjhayden, 2016/08/26 04:53:41]

Thanks!
Now that I know that this count can regularly reach 5 digits, I think that an
exponential histogram would be more appropriate than linear, and, since
exponential histograms are in some sense more efficient, we can probably reduce
the number of bins to match the other histograms?

[Zhen Wang, 2016/08/26 20:52:55]

sgtm

+
   function addTimeDurationValue(valueName, duration, allValues) {
-    var scalarNumericValue = new tr.v.ScalarNumeric(
-        tr.v.Unit.byName.timeDurationInMs_smallerIsBetter, duration);
-    var numericValue = new tr.v.NumericValue(valueName, scalarNumericValue);
-    allValues.addValue(numericValue);
+    var hist = TIME_NUMERIC_BUILDER.build();
+    hist.add(duration);
+    allValues.addValue(new tr.v.NumericValue(valueName, hist));
   }
 
   // Adds values specific to memory-infra dumps.
@@ -65,15 +76,14 @@ tr.exportTo('tr.metrics', function() {
 
     var memoryInfraEventsSize =
         categoryNamesToTotalEventSizes.get(MEMORY_INFRA_TRACING_CATEGORY);
-    var memoryInfraTraceBytesValue = new tr.v.ScalarNumeric(
-        tr.v.Unit.byName.sizeInBytes_smallerIsBetter, memoryInfraEventsSize);
+    var memoryInfraTraceBytesValue = BYTE_NUMERIC_BUILDER.build();
+    memoryInfraTraceBytesValue.add(memoryInfraEventsSize);
     values.addValue(new tr.v.NumericValue(
         'Total trace size of memory-infra dumps in bytes',
         memoryInfraTraceBytesValue));
 
-    var traceBytesPerDumpValue = new tr.v.ScalarNumeric(
-        tr.v.Unit.byName.sizeInBytes_smallerIsBetter,
-        memoryInfraEventsSize / memoryDumpCount);
+    var traceBytesPerDumpValue = BYTE_NUMERIC_BUILDER.build();
+    traceBytesPerDumpValue.add(memoryInfraEventsSize / memoryDumpCount);
     values.addValue(new tr.v.NumericValue(
         'Average trace size of memory-infra dumps in bytes',
         traceBytesPerDumpValue));
@@ -146,12 +156,14 @@ tr.exportTo('tr.metrics', function() {
     var maxEventBytesPerCategory = maxCatNameAndBytes[1];
     var categoryWithMaxEventBytes = maxCatNameAndBytes[0];
 
-    var maxEventCountPerSecValue = new tr.v.ScalarNumeric(
-        tr.v.Unit.byName.unitlessNumber_smallerIsBetter, maxEventCountPerSec);
-    var maxEventBytesPerSecValue = new tr.v.ScalarNumeric(
-        tr.v.Unit.byName.sizeInBytes_smallerIsBetter, maxEventBytesPerSec);
-    var totalTraceBytesValue = new tr.v.ScalarNumeric(
-        tr.v.Unit.byName.sizeInBytes_smallerIsBetter, totalTraceBytes);
+    var maxEventCountPerSecValue = COUNT_NUMERIC_BUILDER.build();
+    maxEventCountPerSecValue.add(maxEventCountPerSec);
+
+    var maxEventBytesPerSecValue = BYTE_NUMERIC_BUILDER.build();
+    maxEventBytesPerSecValue.add(maxEventBytesPerSec);
+
+    var totalTraceBytesValue = BYTE_NUMERIC_BUILDER.build();
+    totalTraceBytesValue.add(totalTraceBytes);
 
     var biggestCategory = {
       name: categoryWithMaxEventBytes,