DevTools: Add grouping by Activity to Timeline treeview.

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

Index: third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineProfileTree.js
diff --git a/third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineProfileTree.js b/third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineProfileTree.js
index 97cd60855f1617967340225a12a450ae4a699bce..be8cca10e046875ecf619b7edecb61cfe070bdbc 100644
--- a/third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineProfileTree.js
+++ b/third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineProfileTree.js
@@ -218,11 +218,11 @@ WebInspector.TimelineProfileTree.eventStackFrame = function(event)
 
 /**
  * @constructor
- * @param {function(!WebInspector.TracingModel.Event):string} categoryMapper
+ * @param {function(!WebInspector.TracingModel.Event):{title: string, category: !WebInspector.TimelineCategory}} eventStyleMapper

[caseq, 2016/06/15 10:04:23]

You can't do this -- category is a UI level notion, so this doesn't compile.

  */
-WebInspector.TimelineAggregator = function(categoryMapper)
+WebInspector.TimelineAggregator = function(eventStyleMapper)
 {
-    this._categoryMapper = categoryMapper;
+    this._eventStyleMapper = eventStyleMapper;
     /** @type {!Map<string, !WebInspector.TimelineProfileTree.Node>} */
     this._groupNodes = new Map();
 }
@@ -232,6 +232,7 @@ WebInspector.TimelineAggregator = function(categoryMapper)
  */
 WebInspector.TimelineAggregator.GroupBy = {
     None: "None",
+    EventName: "EventName",
     Category: "Category",
     Domain: "Domain",
     Subdomain: "Subdomain",
@@ -336,7 +337,8 @@ WebInspector.TimelineAggregator.prototype = {
 
         switch (groupBy) {
         case WebInspector.TimelineAggregator.GroupBy.None: return null;
-        case WebInspector.TimelineAggregator.GroupBy.Category: return node => node.event ? this._categoryMapper(node.event) : "";
+        case WebInspector.TimelineAggregator.GroupBy.EventName: return node => node.event ? this._eventStyleMapper(node.event).title : "";
+        case WebInspector.TimelineAggregator.GroupBy.Category: return node => node.event ? this._eventStyleMapper(node.event).category.name : "";
         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;