DevTools: enable network grouping by default.

third_party/WebKit/Source/devtools/front_end/main/Main.js

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2007 Matt Lilek (pewtermoose@gmail.com).
  * Copyright (C) 2009 Joseph Pecoraro
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
@@ skipping 120 matching lines @@
       if (testPath.indexOf('audits2/') !== -1)
         Runtime.experiments.enableForTest('audits2');
       if (testPath.indexOf('coverage/') !== -1)
         Runtime.experiments.enableForTest('cssTrackerPanel');
       if (testPath.indexOf('changes/') !== -1)
         Runtime.experiments.enableForTest('changesDrawer');
       if (testPath.indexOf('sass/') !== -1)
         Runtime.experiments.enableForTest('liveSASS');
     }
 
-    Runtime.experiments.setDefaultExperiments(
-        ['continueToLocationMarkers', 'autoAttachToCrossProcessSubframes', 'objectPreviews', 'audits2']);
+    Runtime.experiments.setDefaultExperiments([
+      'continueToLocationMarkers', 'autoAttachToCrossProcessSubframes', 'objectPreviews', 'audits2',
+      'networkGroupingRequests'
+    ]);
   }
 
   /**
    * @suppressGlobalPropertiesCheck
    */
   _createAppUI() {
     console.time('Main._createAppUI');
 
     UI.viewManager = new UI.ViewManager();
 
@@ skipping 797 matching lines @@
    * @override
    * @return {?Element}
    */
   settingElement() {
     return UI.SettingsUI.createSettingCheckbox(
         Common.UIString('Show rulers'), Common.moduleSetting('showMetricsRulers'));
   }
 };
 
 new Main.Main();