DevTools: adopt existing Timeline tests for tracing based Timeline

Source/devtools/front_end/components/InspectorView.js

 /*
  * Copyright (C) 2011 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 63 matching lines @@
     this._historyIterator = -1;
     document.addEventListener("keydown", this._keyDown.bind(this), false);
     document.addEventListener("keypress", this._keyPress.bind(this), false);
     this._panelDescriptors = {};
 
     // Windows and Mac have two different definitions of '[' and ']', so accept both of each.
     this._openBracketIdentifiers = ["U+005B", "U+00DB"].keySet();
     this._closeBracketIdentifiers = ["U+005D", "U+00DD"].keySet();
     this._lastActivePanelSetting = WebInspector.settings.createSetting("lastActivePanel", "elements");
 
+    // FIXME(399531): enable timelineOnTraceEvents experiment when running layout tests under inspector/tracing/. This code
+    // should be removed along with the old Timeline implementation once we move tracing based Timeline out of experimental.
+    if ("tracing" === this._lastActivePanelSetting.get()) {
+        WebInspector.experimentsSettings.timelineOnTraceEvents.setEnabled(true);
+        this._lastActivePanelSetting.set("timeline");
+    }
+
     this._loadPanelDesciptors();
 
     InspectorFrontendHost.events.addEventListener(InspectorFrontendHostAPI.Events.ShowConsole, this.showPanel.bind(this, "console"));
 };
 
 WebInspector.InspectorView.prototype = {
     _loadPanelDesciptors: function()
     {
         WebInspector.startBatchUpdate();
         self.runtime.extensions(WebInspector.Panel).forEach(processPanelExtensions.bind(this));
@@ skipping 362 matching lines @@
 
 WebInspector.InspectorView.ToggleDrawerButtonProvider.prototype = {
     /**
      * @return {?WebInspector.StatusBarItem}
      */
     item: function()
     {
         return WebInspector.inspectorView._drawer.toggleButton();
     }
 }