Support counter graphs in Timeline based on trace events

Source/devtools/front_end/timeline/TimelineMemoryOverview.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 50 matching lines @@
         var lowerOffset = 3 * ratio;
         var maxUsedHeapSize = 0;
         var minUsedHeapSize = 100000000000;
         var minTime = this._model.minimumRecordTime();
         var maxTime = this._model.maximumRecordTime();
         /**
          * @param {!WebInspector.TimelineModel.Record} record
          */
         function calculateMinMaxSizes(record)
         {
-            if (record.type() !== WebInspector.TimelineModel.RecordType.UpdateCounters)
-                return;
-            var counters = record.data();
-            if (!counters.jsHeapSizeUsed)
+            var counters = record.counters();
+            if (!counters || !counters.jsHeapSizeUsed)
                 return;
             maxUsedHeapSize = Math.max(maxUsedHeapSize, counters.jsHeapSizeUsed);
             minUsedHeapSize = Math.min(minUsedHeapSize, counters.jsHeapSizeUsed);
         }
         this._model.forAllRecords(calculateMinMaxSizes);
         minUsedHeapSize = Math.min(minUsedHeapSize, maxUsedHeapSize);
 
         var lineWidth = 1;
         var width = this._canvas.width;
         var height = this._canvas.height - lowerOffset;
         var xFactor = width / (maxTime - minTime);
         var yFactor = (height - lineWidth) / Math.max(maxUsedHeapSize - minUsedHeapSize, 1);
 
         var histogram = new Array(width);
 
         /**
          * @param {!WebInspector.TimelineModel.Record} record
          */
         function buildHistogram(record)
         {
-            if (record.type() !== WebInspector.TimelineModel.RecordType.UpdateCounters)
-                return;
-            var counters = record.data();
-            if (!counters.jsHeapSizeUsed)
+            var counters = record.counters();
+            if (!counters || !counters.jsHeapSizeUsed)
                 return;
             var x = Math.round((record.endTime() - minTime) * xFactor);
             var y = Math.round((counters.jsHeapSizeUsed - minUsedHeapSize) * yFactor);
             histogram[x] = Math.max(histogram[x] || 0, y);
         }
         this._model.forAllRecords(buildHistogram);
 
         var ctx = this._context;
         var heightBeyondView = height + lowerOffset + lineWidth;
 
@@ skipping 26 matching lines @@
         ctx.fill();
         ctx.lineWidth = lineWidth;
         ctx.strokeStyle = "hsl(220, 90%, 70%)";
         ctx.stroke();
 
         this._heapSizeLabel.textContent = WebInspector.UIString("%s \u2013 %s", Number.bytesToString(minUsedHeapSize), Number.bytesToString(maxUsedHeapSize));
     },
 
     __proto__: WebInspector.TimelineOverviewBase.prototype
 }