[DevTools] Turn starting tracing into promise.

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

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel 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.
@@ skipping 522 matching lines @@
 
   /**
    * @param {boolean} enabled
    */
   _setUIControlsEnabled(enabled) {
     this._recordingOptionUIControls.forEach(control => control.setEnabled(enabled));
   }
 
   /**
    * @param {boolean} userInitiated
+   * @return {!Promise}
    */
   _startRecording(userInitiated) {
     console.assert(!this._statusPane, 'Status pane is already opened.');
     var mainTarget = SDK.targetManager.mainTarget();
     if (!mainTarget)
-      return;
+      return Promise.resolve();
     this._setState(Timeline.TimelinePanel.State.StartPending);
     this._showRecordingStarted();
 
     this._autoRecordGeneration = userInitiated ? null : Symbol('Generation');
     var enabledTraceProviders = Extensions.extensionServer.traceProviders().filter(
         provider => Timeline.TimelinePanel._settingForTraceProvider(provider).get());
 
     const recordingOptions = {
       enableJSSampling: !this._disableCaptureJSProfileSetting.get(),
       capturePictures: this._captureLayersAndPicturesSetting.get(),
       captureFilmStrip: this._showScreenshotsSetting.get()
     };
 
     this._pendingPerformanceModel = new Timeline.PerformanceModel();
     this._controller = new Timeline.TimelineController(mainTarget, this._pendingPerformanceModel, this);
-    this._controller.startRecording(recordingOptions, enabledTraceProviders);
+    var startPromise = this._controller.startRecording(recordingOptions, enabledTraceProviders);
 
     Host.userMetrics.actionTaken(
         userInitiated ? Host.UserMetrics.Action.TimelineStarted : Host.UserMetrics.Action.TimelinePageReloadStarted);
     this._setUIControlsEnabled(false);
     this._hideLandingPage();
+    return startPromise;
   }
 
   _stopRecording() {
     if (this._statusPane) {
       this._statusPane.finish();
       this._statusPane.updateStatus(Common.UIString('Stopping timeline\u2026'));
       this._statusPane.updateProgressBar(Common.UIString('Received'), 0);
     }
     this._setState(Timeline.TimelinePanel.State.StopPending);
     this._autoRecordGeneration = null;
@@ skipping 100 matching lines @@
      * @param {string} tagName
      * @param {string} contents
      */
     function encloseWithTag(tagName, contents) {
       var e = createElement(tagName);
       e.textContent = contents;
       return e;
     }
 
     var learnMoreNode = UI.createExternalLink(
-        'https://developers.google.com/web/tools/chrome-devtools/evaluate-performance/', Common.UIString('Learn\xa0more'));
+        'https://developers.google.com/web/tools/chrome-devtools/evaluate-performance/',
+        Common.UIString('Learn\xa0more'));
     var recordKey =
         encloseWithTag('b', UI.shortcutRegistry.shortcutDescriptorsForAction('timeline.toggle-recording')[0].name);
     var reloadKey = encloseWithTag('b', UI.shortcutRegistry.shortcutDescriptorsForAction('main.reload')[0].name);
     var navigateNode = encloseWithTag('b', Common.UIString('WASD'));
 
     this._landingPage = new UI.VBox();
     this._landingPage.contentElement.classList.add('timeline-landing-page', 'fill');
     var centered = this._landingPage.contentElement.createChild('div');
 
     var recordButton = UI.Toolbar.createActionButton(this._toggleRecordAction).element;
     var reloadButton = UI.Toolbar.createActionButtonForId('main.reload').element;
 
     centered.createChild('p').appendChild(UI.formatLocalized(
         'Click the record button %s or hit %s to capture a new recording.\n' +
-        'Click the reload button %s or hit %s to record and evaluate the page load.',
+            'Click the reload button %s or hit %s to record and evaluate the page load.',
         [recordButton, recordKey, reloadButton, reloadKey]));
 
     centered.createChild('p').appendChild(UI.formatLocalized(
         'After recording, select an area of interest in the overview by dragging.\n' +
-        'Then, zoom and pan the timeline with the mousewheel or %s keys.\n%s',
+            'Then, zoom and pan the timeline with the mousewheel or %s keys.\n%s',
         [navigateNode, learnMoreNode]));
 
     var cpuProfilerHintSetting = Common.settings.createSetting('timelineShowProfilerHint', true);
     if (cpuProfilerHintSetting.get()) {
       var warning = centered.createChild('p', 'timeline-landing-warning');
       var closeButton = warning.createChild('div', 'timeline-landing-warning-close', 'dt-close-button');
       closeButton.addEventListener('click', () => {
         warning.style.visibility = 'hidden';
         cpuProfilerHintSetting.set(false);
       }, false);
@@ skipping 102 matching lines @@
     }
     this._overviewPane.setMarkers(markers);
   }
 
   /**
    * @param {!Common.Event} event
    */
   _pageReloadRequested(event) {
     if (this._state !== Timeline.TimelinePanel.State.Idle || !this.isShowing())
       return;
-    this._startRecording(false);
+    var resourceTreeModel = /** @type {!SDK.ResourceTreeModel} */ (event.data);
+    resourceTreeModel.suspendReload();
+    this._startRecording(false).then(() => resourceTreeModel.resumeReload());
   }
 
   /**
    * @param {!Common.Event} event
    */
   _loadEventFired(event) {
     if (this._state !== Timeline.TimelinePanel.State.Recording || !this._autoRecordGeneration)
       return;
     setTimeout(stopRecordingOnReload.bind(this, this._autoRecordGeneration), this._millisecondsToRecordAfterLoadEvent);
 
@@ skipping 494 matching lines @@
         return true;
       case 'timeline.jump-to-next-frame':
         panel._jumpToFrame(1);
         return true;
     }
     return false;
   }
 };
 
 Timeline.TimelinePanel._traceProviderSettingSymbol = Symbol('traceProviderSetting');