Force non overlay scrollbar in Devtools/Performance for Aura Overlay Scrollbar

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

 /*
  * Copyright (C) 2011 Google Inc.  All rights reserved.
  * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2007 Matt Lilek (pewtermoose@gmail.com).
  * Copyright (C) 2009 Joseph Pecoraro
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
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   return Common.UIString('Async Call');
 };
 
 /**
  * @param {!Element} element
  */
 UI.installComponentRootStyles = function(element) {
   UI.appendStyle(element, 'ui/inspectorCommon.css');
   UI.themeSupport.injectHighlightStyleSheets(element);
   element.classList.add('platform-' + Host.platform());
+
+  /**
+   * Detect overlay scrollbar enable by checking clientWidth and offsetWidth of
+   * overflow: scroll div.
+   * @param {?Document=} document
+   * @return {boolean}
+   */
+  function overlayScrollbarEnabled(document) {
+    var scrollDiv = document.createElement('div');
+    scrollDiv.setAttribute('style', 'width: 100px; height: 100px; overflow: scroll;');
+    document.body.appendChild(scrollDiv);
+    var scrollbarWidth = scrollDiv.offsetWidth - scrollDiv.clientWidth;
+    document.body.removeChild(scrollDiv);
+    return scrollbarWidth === 0;
+  }
+
+  if (!Host.isMac() && overlayScrollbarEnabled(element.ownerDocument))
+    element.classList.add('overlay-scrollbar-enabled');
 };
 
 /**
  * @param {!Element} element
  * @param {string=} cssFile
  * @return {!DocumentFragment}
  */
 UI.createShadowRootWithCoreStyles = function(element, cssFile) {
   var shadowRoot = element.createShadowRoot();
   UI.appendStyle(shadowRoot, 'ui/inspectorCommon.css');
@@ skipping 1339 matching lines @@
  */
 UI.createInlineButton = function(toolbarButton) {
   var element = createElement('span');
   var shadowRoot = UI.createShadowRootWithCoreStyles(element, 'ui/inlineButton.css');
   element.classList.add('inline-button');
   var toolbar = new UI.Toolbar('');
   toolbar.appendToolbarItem(toolbarButton);
   shadowRoot.appendChild(toolbar.element);
   return element;
 };