DevTools: add Tracing agent on back-end

Source/devtools/front_end/timeline/TimelinePanel.js

Index: Source/devtools/front_end/timeline/TimelinePanel.js
diff --git a/Source/devtools/front_end/timeline/TimelinePanel.js b/Source/devtools/front_end/timeline/TimelinePanel.js
index 7abac84c4833159afc380541a794990c9eb398d2..29c65941d17eec93b8e9d3de129a2af201c8d87b 100644
--- a/Source/devtools/front_end/timeline/TimelinePanel.js
+++ b/Source/devtools/front_end/timeline/TimelinePanel.js
@@ -143,6 +143,8 @@ WebInspector.TimelinePanel.headerHeight = 20;
 
 WebInspector.TimelinePanel.durationFilterPresetsMs = [0, 1, 15];
 
+WebInspector.TimelinePanel.defaultTracingCategoryFilter = "*,disabled-by-default-cc.debug,disabled-by-default-devtools.timeline";
+
 WebInspector.TimelinePanel.prototype = {
     /**
      * @return {?WebInspector.SearchableView}
@@ -250,6 +252,7 @@ WebInspector.TimelinePanel.prototype = {
         if (!this._lazyTracingModel) {
             this._lazyTracingModel = new WebInspector.TracingModel();
             this._lazyTracingModel.addEventListener(WebInspector.TracingModel.Events.BufferUsage, this._onTracingBufferUsage, this);
+            this._lazyTracingModel.enable(WebInspector.TimelinePanel.defaultTracingCategoryFilter);
         }
         return this._lazyTracingModel;
     },
@@ -622,7 +625,7 @@ WebInspector.TimelinePanel.prototype = {
         this._userInitiatedRecording = userInitiated;
         this._model.startRecording(this._captureStacksSetting.get(), this._captureMemorySetting.get());
         if (WebInspector.experimentsSettings.timelineTracingMode.isEnabled())
-            this._tracingModel().start(WebInspector.TimelineManager.defaultTracingCategories, "");
+            this._tracingModel().start(WebInspector.TimelinePanel.defaultTracingCategoryFilter, "");
         for (var i = 0; i < this._overviewControls.length; ++i)
             this._overviewControls[i].timelineStarted();