DevTools: Unify main thread name across vanilla and tracing timeline modes.

Source/devtools/front_end/timeline/TimelineFlameChart.js

 /*
  * Copyright (C) 2014 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 128 matching lines @@
         this._pushRecord(this._cpuThreadRecord, 0, this.minimumBoundary(), Math.max(this._model.maximumRecordTime(), this.totalTime() + this.minimumBoundary()));
 
         this._gpuThreadRecord = null;
 
         var records = this._model.records();
         for (var i = 0; i < records.length; ++i) {
             var record = records[i];
             var thread = record.thread();
             if (thread === "gpu")
                 continue;
-            if (!thread) {
+            if (thread === WebInspector.TimelineModel.MainThreadName) {
                 for (var j = 0; j < record.children().length; ++j)
                     this._appendRecord(record.children()[j], 1);
             } else {
                 var visible = this._appendRecord(records[i], 1);
                 if (visible && !this._gpuThreadRecord) {
                     var gpuThreadRecordPayload = { type: WebInspector.TimelineModel.RecordType.Program };
                     this._gpuThreadRecord = new WebInspector.TimelineModel.RecordImpl(this._model, /** @type {!TimelineAgent.TimelineEvent} */ (gpuThreadRecordPayload), null);
                     this._pushRecord(this._gpuThreadRecord, 0, this.minimumBoundary(), Math.max(this._model.maximumRecordTime(), this.totalTime() + this.minimumBoundary()));
                 }
             }
         }
 
-        var cpuStackDepth = Math.max(4, this._entryThreadDepths[undefined]);
-        delete this._entryThreadDepths[undefined];
+        var cpuStackDepth = Math.max(4, this._entryThreadDepths[WebInspector.TimelineModel.MainThreadName]);
+        delete this._entryThreadDepths[WebInspector.TimelineModel.MainThreadName];
         this._maxStackDepth = cpuStackDepth;
 
         if (this._gpuThreadRecord) {
             // We have multiple threads, update levels.
             var threadBaselines = {};
             var threadBaseline = cpuStackDepth + 2;
 
             for (var thread in this._entryThreadDepths) {
                 threadBaselines[thread] = threadBaseline;
                 threadBaseline += this._entryThreadDepths[thread];
             }
             this._maxStackDepth = threadBaseline;
 
             for (var i = 0; i < this._records.length; ++i) {
                 var record = this._records[i];
                 var level = this._timelineData.entryLevels[i];
                 if (record === this._cpuThreadRecord)
                     level = 0;
                 else if (record === this._gpuThreadRecord)
                     level = cpuStackDepth + 2;
-                else if (record.thread())
+                else if (record.thread() !== WebInspector.TimelineModel.MainThreadName)
                     level += threadBaselines[record.thread()];
                 this._timelineData.entryLevels[i] = level;
             }
         }
 
         return this._timelineData;
     },
 
     /**
      * @return {number}
@@ skipping 776 matching lines @@
      * @param {number} entryIndex
      * @return {?WebInspector.TimelineSelection}
      */
     createSelection: function(entryIndex) { },
     /**
      * @param {?WebInspector.TimelineSelection} selection
      * @return {number}
      */
     entryIndexForSelection: function(selection) { }
 }