DevTools: TabbedLocations only materialize tabs when needed

third_party/WebKit/Source/devtools/front_end/ui/TabbedPane.js

 /*
  * Copyright (C) 2010 Google 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 422 matching lines @@
     this._updateTabElements();
   }
 
   /**
    * @override
    */
   wasShown() {
     var effectiveTab = this._currentTab || this._tabsHistory[0];
     if (effectiveTab && this._autoSelectFirstItemOnShow)
       this.selectTab(effectiveTab.id);
+    this.dispatchEventToListeners(UI.TabbedPane.Events.TabsShown, this._currentTab);
   }
 
   /**
    * @param {boolean} enable
    */
   setTabSlider(enable) {
     this._sliderEnabled = enable;
     this._tabSlider.classList.toggle('enabled', enable);
     this._headerElement.classList.add('tabbed-pane-no-tab-borders');
   }
@@ skipping 371 matching lines @@
   setAllowTabReorder(allow, automatic) {
     this._allowTabReorder = allow;
     this._automaticReorder = automatic;
   }
 };
 
 /** @enum {symbol} */
 UI.TabbedPane.Events = {
   TabSelected: Symbol('TabSelected'),
   TabClosed: Symbol('TabClosed'),
-  TabOrderChanged: Symbol('TabOrderChanged')
+  TabOrderChanged: Symbol('TabOrderChanged'),
+  TabsShown: Symbol('TabsShown')
 };
 
 /**
  * @unrestricted
  */
 UI.TabbedPaneTab = class {
   /**
    * @param {!UI.TabbedPane} tabbedPane
    * @param {string} id
    * @param {string} title
@@ skipping 358 matching lines @@
    * @param {!Array.<string>} ids
    */
   closeTabs(tabbedPane, ids) {},
 
   /**
    * @param {string} tabId
    * @param {!UI.ContextMenu} contextMenu
    */
   onContextMenu(tabId, contextMenu) {}
 };