Timeline: add experiment to show events from subframes in the frames of their own

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

 /*
  * Copyright (C) 2013 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 1720 matching lines @@
         span.appendChild(WebInspector.linkifyURLAsNode(
             'https://github.com/GoogleChrome/devtools-docs/issues/53', WebInspector.UIString('Not optimized'),
             undefined, true));
         span.createTextChild(WebInspector.UIString(': %s', eventData['deoptReason']));
         break;
       default:
         console.assert(false, 'Unhandled TimelineModel.WarningType');
     }
     return span;
   }
+
+  /**
+   * @param {!WebInspector.TimelineModel.PageFrame} frame
+   * @param {number=} trimAt
+   */
+  static displayNameForFrame(frame, trimAt) {
+    var url = frame.url;
+    if (!trimAt)
+      trimAt = 30;
+    return url.startsWith('about:') ? `"${frame.name.trimMiddle(trimAt)}"` : frame.url.trimEnd(trimAt);
+  }
 };
 
 /**
  * @unrestricted
  */
 WebInspector.TimelineRecordStyle = class {
   /**
    * @param {string} title
    * @param {!WebInspector.TimelineCategory} category
    * @param {boolean=} hidden
@@ skipping 462 matching lines @@
   /**
    * @param {!WebInspector.TracingModel.Event} event
    * @param {string=} warningType
    */
   appendWarningRow(event, warningType) {
     var warning = WebInspector.TimelineUIUtils.eventWarning(event, warningType);
     if (warning)
       this.appendElementRow(WebInspector.UIString('Warning'), warning, true);
   }
 };