Timeline: do not start timeline on regular page reloads

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

 // Copyright 2016 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.
 
 /**
  * @implements {SDK.SDKModelObserver<!SDK.CPUProfilerModel>}
  * @implements {SDK.TracingManagerClient}
  * @unrestricted
  */
 Timeline.TimelineController = class {
@@ skipping 11 matching lines @@
     this._tracingModel = new SDK.TracingModel(this._tracingModelBackingStorage);
 
     this._performanceModel.setMainTarget(tracingManager.target());
 
     /** @type {!Array<!Timeline.ExtensionTracingSession>} */
     this._extensionSessions = [];
     SDK.targetManager.observeModels(SDK.CPUProfilerModel, this);
   }
 
   /**
+   * @return {!SDK.Target}
+   */
+  mainTarget() {
+    return this._tracingManager.target();
+  }
+
+  /**
    * @param {!Timeline.TimelineController.RecordingOptions} options
    * @param {!Array<!Extensions.ExtensionTraceProvider>} providers
    * @return {!Promise}
    */
   startRecording(options, providers) {
     this._extensionTraceProviders = Extensions.extensionServer.traceProviders().slice();
 
     /**
      * @param {string} category
      * @return {string}
@@ skipping 230 matching lines @@
 };
 
 /**
  * @typedef {!{
  *   enableJSSampling: (boolean|undefined),
  *   capturePictures: (boolean|undefined),
  *   captureFilmStrip: (boolean|undefined)
  * }}
  */
 Timeline.TimelineController.RecordingOptions;