Timeline: rearrange trace completion logic for better extensibility

This generalize the way we finialize timeline recording so that it's
easier to plug in extension trace providers.

BUG=620066

Review-Url: https://codereview.chromium.org/2137213004
Cr-Commit-Position: refs/heads/master@{#405918}

third_party/WebKit/LayoutTests/inspector/tracing/trace-event-self-time.html

@@ -287,12 +287,10 @@ function test()
     var timelineController = InspectorTest.timelineController();
     timelineController._addCpuProfile(WebInspector.targetManager.mainTarget().id(), null, cpuProfile);
     timelineController.traceEventsCollected(rawTraceEvents);
-    timelineController.tracingComplete();
-    InspectorTest.addSniffer(WebInspector.panels.timeline, "loadingComplete", () => {
-        var events = InspectorTest.timelineModel().inspectedTargetEvents();
-        events.forEach(e => InspectorTest.addResult(e.name + ": " + e.startTime + " " + (e.selfTime || 0).toFixed(2) + "/" + (e.duration || 0).toFixed(2)));
-        InspectorTest.completeTest();
-    });
+    timelineController._allSourcesFinished();
+    var events = InspectorTest.timelineModel().inspectedTargetEvents();
+    events.forEach(e => InspectorTest.addResult(e.name + ": " + e.startTime + " " + (e.selfTime || 0).toFixed(2) + "/" + (e.duration || 0).toFixed(2)));
+    InspectorTest.completeTest();
 }
 
 </script>

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

@@ -16,8 +16,6 @@ WebInspector.TimelineController = function(target, delegate, tracingModel)
     this._target = target;
     this._tracingModel = tracingModel;
     this._targets = [];
-    this._allProfilesStoppedPromise = Promise.resolve();
-    this._targetsResumedPromise = Promise.resolve();
     WebInspector.targetManager.observeTargets(this);
 }
 
@@ -73,9 +71,13 @@ WebInspector.TimelineController.prototype = {
 
     stopRecording: function()
     {
-        this._allProfilesStoppedPromise = this._stopProfilingOnAllTargets();
+        var tracingStoppedPromises = [];
+        tracingStoppedPromises.push(new Promise(resolve => this._tracingCompleteCallback = resolve));
+        tracingStoppedPromises.push(this._stopProfilingOnAllTargets());
         this._target.tracingManager.stop();
-        this._targetsResumedPromise = WebInspector.targetManager.resumeAllTargets();
+        tracingStoppedPromises.push(WebInspector.targetManager.resumeAllTargets());
+        Promise.all(tracingStoppedPromises).then(() => this._allSourcesFinished());
+
         this._delegate.loadingStarted();
     },
 
@@ -206,11 +208,11 @@ WebInspector.TimelineController.prototype = {
      */
     tracingComplete: function()
     {
-        Promise.all([this._allProfilesStoppedPromise, this._targetsResumedPromise])
-            .then(this._didStopRecordingTraceEvents.bind(this));
+        this._tracingCompleteCallback();
+        this._tracingCompleteCallback = null;
     },
 
-    _didStopRecordingTraceEvents: function()
+    _allSourcesFinished: function()
     {
         this._injectCpuProfileEvents();
         this._tracingModel.tracingComplete();