Timeline: rearrange trace completion logic for better extensibility

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

Index: third_party/WebKit/Source/devtools/front_end/timeline/TimelineController.js
diff --git a/third_party/WebKit/Source/devtools/front_end/timeline/TimelineController.js b/third_party/WebKit/Source/devtools/front_end/timeline/TimelineController.js
index 3ce1bc2a3b2d5eb85e22af33d1ca022a59eb61d4..6bc49a7d197ea8434c9f6ec5d4a3dacffa662b13 100644
--- a/third_party/WebKit/Source/devtools/front_end/timeline/TimelineController.js
+++ b/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();