DevTools: Add grouping by Activity to Timeline treeview.

third_party/WebKit/Source/devtools/front_end/timeline/TimelineProfileTree.js

 // Copyright 2016 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.
 
 WebInspector.TimelineProfileTree = { };
 
 /**
  * @constructor
  */
 WebInspector.TimelineProfileTree.Node = function()
@@ skipping 214 matching lines @@
     this._categoryMapper = categoryMapper;
     /** @type {!Map<string, !WebInspector.TimelineProfileTree.Node>} */
     this._groupNodes = new Map();
 }
 
 /**
  * @enum {string}
  */
 WebInspector.TimelineAggregator.GroupBy = {
     None: "None",
+    EventName: "EventName",
     Category: "Category",
     Domain: "Domain",
     Subdomain: "Subdomain",
     URL: "URL"
 }
 
 /**
  * @param {!WebInspector.TracingModel.Event} event
  * @return {string}
  */
@@ skipping 84 matching lines @@
             if (!groupSubdomains)
                 return parsedURL.host;
             if (/^[.0-9]+$/.test(parsedURL.host))
                 return parsedURL.host;
             var domainMatch = /([^.]*\.)?[^.]*$/.exec(parsedURL.host);
             return domainMatch && domainMatch[0] || "";
         }
 
         switch (groupBy) {
         case WebInspector.TimelineAggregator.GroupBy.None: return null;
+        case WebInspector.TimelineAggregator.GroupBy.EventName: return node => node.event.name;

[alph, 2016/05/26 07:23:20]

Can event be null? There's a check on the next line.

         case WebInspector.TimelineAggregator.GroupBy.Category: return node => node.event ? this._categoryMapper(node.event) : "";
         case WebInspector.TimelineAggregator.GroupBy.Subdomain: return groupByDomain.bind(null, false);
         case WebInspector.TimelineAggregator.GroupBy.Domain: return groupByDomain.bind(null, true);
         case WebInspector.TimelineAggregator.GroupBy.URL: return groupByURL;
         default: return null;
         }
     },
 
     /**
      * @param {string} id
@@ skipping 17 matching lines @@
      * @param {function(!WebInspector.TimelineProfileTree.Node):string} nodeToGroupId
      * @param {!WebInspector.TimelineProfileTree.Node} node
      * @return {!WebInspector.TimelineProfileTree.Node}
      */
     _nodeToGroupNode: function(nodeToGroupId, node)
     {
         var id = nodeToGroupId(node);
         return this._groupNodes.get(id) || this._buildGroupNode(id, node.event);
     },
 }