DevTools: Switch to using fast stack iterator to collect stacks during timeline recording.

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

 // Copyright 2014 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.TimelineJSProfileProcessor = { };
 
 /**
  * @param {!ProfilerAgent.CPUProfile} jsProfile
  * @param {!WebInspector.TracingModel.Thread} thread
@@ skipping 136 matching lines @@
             if (depth < lockedDepth) {
                 console.error("Child stack is shallower (" + depth + ") than the parent stack (" + lockedDepth + ") at " + time);
                 depth = lockedDepth;
             }
         }
         if (jsFramesStack.length < depth) {
             console.error("Trying to truncate higher than the current stack size at " + time);
             depth = jsFramesStack.length;
         }
         var minFrameDurationMs = currentSamplingIntervalMs / 2;
+        for (var k = 0; k < depth; ++k)
+            jsFramesStack[k].setEndTime(time);
         for (var k = depth; k < jsFramesStack.length; ++k)
             jsFramesStack[k].setEndTime(Math.min(eventEndTime(jsFramesStack[k]) + minFrameDurationMs, time));
         jsFramesStack.length = depth;
     }
 
     /**
      * @param {!Array<!ConsoleAgent.CallFrame>} stack
      */
     function filterStackFrames(stack)
     {
         for (var i = 0, j = 0; i < stack.length; ++i) {
             var url = stack[i].url;
             if (url && url.startsWith("native "))
                 continue;
             stack[j++] = stack[i];
         }
         stack.length = j;
     }
 
     /**
      * @param {!WebInspector.TracingModel.Event} e
      */
     function extractStackTrace(e)
     {
-        var eventData = e.args["data"] || e.args["beginData"];
-        var stackTrace = eventData && eventData["stackTrace"];
         var recordTypes = WebInspector.TimelineModel.RecordType;
-        // GC events do not hold call stack, so make a copy of the current stack.
-        if (e.name === recordTypes.GCEvent || e.name === recordTypes.MajorGC || e.name === recordTypes.MinorGC)
-            stackTrace = jsFramesStack.map(function(frameEvent) { return frameEvent.args["data"]; }).reverse();
-        if (!stackTrace)
-            return;
+        var stackTrace;

[pfeldman, 2016/01/27 23:42:27]

Annotate the type please.

[alph, 2016/01/27 23:51:20]

Done.

+        if (e.name === recordTypes.JSSample) {
+            var eventData = e.args["data"] || e.args["beginData"];
+            stackTrace = eventData && eventData["stackTrace"];
+        } else {
+            stackTrace = jsFramesStack.map(frameEvent => frameEvent.args["data"]).reverse();
+        }
         if (filterNativeFunctions)
             filterStackFrames(stackTrace);
         var endTime = eventEndTime(e);
         var numFrames = stackTrace.length;
         var minFrames = Math.min(numFrames, jsFramesStack.length);
         var i;
         for (i = lockedJsStackDepth.peekLast() || 0; i < minFrames; ++i) {
             var newFrame = stackTrace[numFrames - 1 - i];
             var oldFrame = jsFramesStack[i].args["data"];
             if (!equalFrames(newFrame, oldFrame))
                 break;
             jsFramesStack[i].setEndTime(Math.max(jsFramesStack[i].endTime, endTime));
         }
         truncateJSStack(i, e.startTime);
         for (; i < numFrames; ++i) {
             var frame = stackTrace[numFrames - 1 - i];
-            var jsFrameEvent = new WebInspector.TracingModel.Event(WebInspector.TracingModel.DevToolsTimelineEventCategory, WebInspector.TimelineModel.RecordType.JSFrame,
+            var jsFrameEvent = new WebInspector.TracingModel.Event(WebInspector.TracingModel.DevToolsTimelineEventCategory, recordTypes.JSFrame,
                 WebInspector.TracingModel.Phase.Complete, e.startTime, e.thread);
             jsFrameEvent.ordinal = e.ordinal;
             jsFrameEvent.addArgs({ data: frame });
             jsFrameEvent.setEndTime(endTime);
             jsFramesStack.push(jsFrameEvent);
             jsFrameEvents.push(jsFrameEvent);
         }
     }
 
     /**
@@ skipping 289 matching lines @@
                 WebInspector.TracingModel.Phase.Instant, e.startTime, e.thread);
             sampleEvent.ordinal = e.ordinal;
             sampleEvent.args = {"data": {"stackTrace": stack }};
             samples.push(sampleEvent);
             break;
         }
     }
 
     return samples;
 }