DevTools: [timeline tree view] (unattributed) costs include extension overhead in Domain grouping

Source/devtools/front_end/timeline/TimelineTreeView.js

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @constructor
  * @extends {WebInspector.VBox}
  * @param {!WebInspector.TimelineModel} model
  */
 WebInspector.TimelineTreeView = function(model)
@@ skipping 170 matching lines @@
             return WebInspector.TimelineTreeView.eventURL(node.event) || "";
         }
 
         /**
          * @param {boolean} groupSubdomains
          * @param {!WebInspector.TimelineModel.ProfileTreeNode} node
          * @return {string}
          */
         function groupByDomain(groupSubdomains, node)
         {
-            var parsedURL = (WebInspector.TimelineTreeView.eventURL(node.event) || "").asParsedURL();
+            var url = WebInspector.TimelineTreeView.eventURL(node.event) || "";
+            if (url.startsWith("extensions::"))
+                return groupSubdomains ? WebInspector.UIString("Chrome Extensions Overhead") : url;
+            var parsedURL = url.asParsedURL();
             if (!parsedURL)
                 return "";
             if (parsedURL.scheme === "chrome-extension") {
-                var url = parsedURL.scheme + "://" + parsedURL.host;
+                url = parsedURL.scheme + "://" + parsedURL.host;
                 var displayName = executionContextNamesByOrigin.get(url);
                 return displayName ? WebInspector.UIString("Chrome Extension: %s", displayName) : url;
             }
             if (!groupSubdomains)
                 return parsedURL.host;
             if (/^[.0-9]+$/.test(parsedURL.host))
                 return parsedURL.host;
             var domainMatch = /([^.]*\.)?[^.]*$/.exec(parsedURL.host);
             return domainMatch && domainMatch[0] || "";
         }
@@ skipping 207 matching lines @@
         if (!this._profileNode.children)
             return;
         for (var node of this._profileNode.children.values()) {
             var gridNode = new WebInspector.TimelineTreeView.GridNode(node, this._totalTime, this._maxTimes.self, this._maxTimes.total);
             this.insertChildOrdered(gridNode);
         }
     },
 
     __proto__: WebInspector.SortableDataGridNode.prototype
 }