DevTools: enable network grouping by default.

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

Index: third_party/WebKit/Source/devtools/front_end/main/Main.js
diff --git a/third_party/WebKit/Source/devtools/front_end/main/Main.js b/third_party/WebKit/Source/devtools/front_end/main/Main.js
index cfd98b69bd9b0743584dfbfc10ee3ae4074f77b5..f0931a67356978e0c3eedb6739007893cb9f8224 100644
--- a/third_party/WebKit/Source/devtools/front_end/main/Main.js
+++ b/third_party/WebKit/Source/devtools/front_end/main/Main.js
@@ -138,8 +138,10 @@ Main.Main = class {
         Runtime.experiments.enableForTest('liveSASS');
     }
 
-    Runtime.experiments.setDefaultExperiments(
-        ['continueToLocationMarkers', 'autoAttachToCrossProcessSubframes', 'objectPreviews', 'audits2']);
+    Runtime.experiments.setDefaultExperiments([
+      'continueToLocationMarkers', 'autoAttachToCrossProcessSubframes', 'objectPreviews', 'audits2',
+      'networkGroupingRequests'
+    ]);
   }
 
   /**