DevTools: all swatches should have a default focused element

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

 /*
  * Copyright (C) 2009 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 65 matching lines @@
    * @param {?number=} preferredWidth
    * @param {?number=} preferredHeight
    * @param {?UI.Popover.Orientation=} arrowDirection
    */
   _innerShow(view, contentElement, anchor, preferredWidth, preferredHeight, arrowDirection) {
     if (this._disposed)
       return;
     this._contentElement = contentElement;
 
     // This should not happen, but we hide previous popup to be on the safe side.
-    if (UI.Popover._popover)
+    var restoreFocus;
+    if (UI.Popover._popover) {
+      restoreFocus = UI.Popover._popover.hasFocus();
       UI.Popover._popover.hide();
+    }
     UI.Popover._popover = this;
 
     var document = anchor instanceof Element ? anchor.ownerDocument : contentElement.ownerDocument;
     var window = document.defaultView;
 
     // Temporarily attach in order to measure preferred dimensions.
     var preferredSize = view ? view.measurePreferredSize() : UI.measurePreferredSize(this._contentElement);
     this._preferredWidth = preferredWidth || preferredSize.width;
     this._preferredHeight = preferredHeight || preferredSize.height;
 
     window.addEventListener('resize', this._hideBound, false);
     document.body.appendChild(this._containerElement);
     super.show(this._containerElement);
+    if (restoreFocus && view)
+      view.focus();

[dgozman, 2016/11/17 01:29:50]

How do you focus view before showing it in line 108?

[luoe, 2016/11/17 21:38:08]

Ahh, good point.  We should restore focus after the view/contentElement is
showing.

 
     if (view)
       view.show(this._contentDiv);
     else
       this._contentDiv.appendChild(this._contentElement);
 
     this.positionElement(anchor, this._preferredWidth, this._preferredHeight, arrowDirection);
 
     if (this._popoverHelper) {
       this._contentDiv.addEventListener(
@@ skipping 293 matching lines @@
       this._resetHoverTimer();
     }
   }
 };
 
 /** @enum {string} */
 UI.Popover.Orientation = {
   Top: 'top',
   Bottom: 'bottom'
 };