DevTools: Show top level event initiator when a child is selected.

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

 /*
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 847 matching lines @@
 
   /**
    * @param {number} entryIndex
    * @return {boolean}
    */
   buildFlowForInitiator(entryIndex) {
     if (this._lastInitiatorEntry === entryIndex)
       return false;
     this._lastInitiatorEntry = entryIndex;
     var event = this.eventByIndex(entryIndex);
-    var initiator = event && TimelineModel.TimelineData.forEvent(event).initiator();
-    if (initiator && !this._isVisible(initiator))
-      initiator = null;
     var td = this._timelineData;
-    if (td.flowStartTimes.length || initiator) {
-      td.flowStartTimes = [];
-      td.flowStartLevels = [];
-      td.flowEndTimes = [];
-      td.flowEndLevels = [];
+    td.flowStartTimes = [];
+    td.flowStartLevels = [];
+    td.flowEndTimes = [];
+    td.flowEndLevels = [];
+    // Find the closest ancestor with an initiator.
+    var initiator;
+    for (; event; event = TimelineModel.TimelineModel.parentEvent(event)) {
+      if (!this._isVisible(event))
+        continue;
+      initiator = TimelineModel.TimelineData.forEvent(event).initiator();
+      if (initiator)
+        break;
     }
-    if (!initiator)
+    if (!event || !initiator || !this._isVisible(initiator))

[caseq, 2017/03/29 22:08:20]

nit: first clause is redundant

[alph, 2017/03/29 22:16:57]

Done.

       return true;
+    var eventIndex = event[Timeline.TimelineFlameChartDataProvider._indexSymbol];
     var initiatorIndex = initiator[Timeline.TimelineFlameChartDataProvider._indexSymbol];
-    var eventIndex = event[Timeline.TimelineFlameChartDataProvider._indexSymbol];
     td.flowStartTimes.push(initiator.endTime || initiator.startTime);
     td.flowStartLevels.push(td.entryLevels[initiatorIndex]);
     td.flowEndTimes.push(event.startTime);
     td.flowEndLevels.push(td.entryLevels[eventIndex]);
     return true;
   }
 
   /**
    * @param {number} entryIndex
    * @return {?SDK.TracingModel.Event}
    */
   eventByIndex(entryIndex) {
     return this._entryType(entryIndex) === Timeline.TimelineFlameChartEntryType.Event ?
         /** @type {!SDK.TracingModel.Event} */ (this._entryData[entryIndex]) :
         null;
   }
 };
 
 Timeline.TimelineFlameChartDataProvider.InstantEventVisibleDurationMs = 0.001;
 Timeline.TimelineFlameChartDataProvider._indexSymbol = Symbol('index');