Layers that have a backdrop-filter should paints contents

third_party/WebKit/Source/core/style/ComputedStyle.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 399 matching lines @@
     bool isFloating() const { return noninherited_flags.floating != NoFloat; }
     bool hasMargin() const { return surround->margin.nonZero(); }
     bool hasBorderFill() const { return surround->border.hasBorderFill(); }
     bool hasBorder() const { return surround->border.hasBorder(); }
     bool hasBorderDecoration() const { return hasBorder() || hasBorderFill(); }
     bool hasPadding() const { return surround->padding.nonZero(); }
     bool hasMarginBeforeQuirk() const { return marginBefore().quirk(); }
     bool hasMarginAfterQuirk() const { return marginAfter().quirk(); }
 
     bool hasBackgroundImage() const { return m_background->background().hasImage(); }
+    bool hasBackgroundImageOrBackdropFilter() const { return hasBackgroundImage() || hasBackdropFilter(); }
     bool hasFixedBackgroundImage() const { return m_background->background().hasFixedImage(); }
 
     bool hasEntirelyFixedBackground() const;
 
     bool hasAppearance() const { return appearance() != NoControlPart; }
 
     bool hasBackgroundRelatedColorReferencingCurrentColor() const
     {
         if (backgroundColor().isCurrentColor() || visitedLinkBackgroundColor().isCurrentColor())
             return true;
         if (!boxShadow())
             return false;
         return shadowListHasCurrentColor(boxShadow());
     }
 
     bool hasBackground() const
     {
         Color color = visitedDependentColor(CSSPropertyBackgroundColor);
         if (color.alpha())
             return true;
-        return hasBackgroundImage();
+        return hasBackgroundImageOrBackdropFilter();

[pdr., 2016/01/27 05:52:09]

Is this tested? This was my concern in the previous review.

I looked at some callsites of style->hasBackground() and I'm not sure this is
correct. Just as an example, LayoutBoxModelObject::backgroundStolenForBeingBody
has a hasBackground call... is it correct to return false if there's a backdrop
filter?

Renaming this to be hasBackgroundOrBackdropFilter might help as well, but I'm
primarily worried about the edge-case bugs this introduces.

[jaydasika, 2016/01/27 23:59:42]

Ah, I see your point. I think we should have a separate hasBackdropFilter,
because we can't have it in hasBackground(for the reasons you mentioned) and not
in hasBoxDecorations (for reasons mentioned in the previous review). WDYT ?     

     }
 
     LayoutRectOutsets imageOutsets(const NinePieceImage&) const;
     bool hasBorderImageOutsets() const
     {
         return borderImage().hasImage() && borderImage().outset().nonZero();
     }
     LayoutRectOutsets borderImageOutsets() const
     {
         return imageOutsets(borderImage());
@@ skipping 1566 matching lines @@
 }
 
 inline bool ComputedStyle::hasPseudoElementStyle() const
 {
     return noninherited_flags.pseudoBits & PSEUDO_ELEMENT_MASK;
 }
 
 } // namespace blink
 
 #endif // ComputedStyle_h