DevTools: Split Timeline started UMA metric into two parts.

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 535 matching lines @@
         provider => Timeline.TimelinePanel._settingForTraceProvider(provider).get());
 
     const recordingOptions = this._landingPage.recordingOptions();
     this._controller = new Timeline.TimelineController(mainTarget, this, this._tracingModel);
     this._controller.startRecording(recordingOptions, enabledTraceProviders);
     this._recordingStartTime = Date.now();
 
     for (var i = 0; i < this._overviewControls.length; ++i)
       this._overviewControls[i].timelineStarted();
 
-    Host.userMetrics.actionTaken(Host.UserMetrics.Action.TimelineStarted);
+    Host.userMetrics.actionTaken(userInitiated ? Host.UserMetrics.Action.TimelineStarted : Host.UserMetrics.Action.TimelinePageReloadStarted);
     this._setUIControlsEnabled(false);
     this._hideLandingPage();
   }
 
   _stopRecording() {
     if (this._statusPane) {
       this._statusPane.finish();
       this._statusPane.updateStatus(Common.UIString('Stopping timeline\u2026'));
       this._statusPane.updateProgressBar(Common.UIString('Received'), 0);
     }
@@ skipping 1353 matching lines @@
   }
 
   /**
    * @override
    * @param {!SDK.Target} target
    */
   targetRemoved(target) {
     this._targets.remove(target, true);
   }
 };