blink: Layers that have a backdrop-filter paints contents

Source/core/style/ComputedStyle.h

Index: Source/core/style/ComputedStyle.h
diff --git a/Source/core/style/ComputedStyle.h b/Source/core/style/ComputedStyle.h
index a52eabc06ef1b7b06dd4ff4666441073408d3f64..87b4be4a33905be38df9355b5ff8374f8789c366 100644
--- a/Source/core/style/ComputedStyle.h
+++ b/Source/core/style/ComputedStyle.h
@@ -422,7 +422,7 @@ public:
         Color color = visitedDependentColor(CSSPropertyBackgroundColor);
         if (color.alpha())
             return true;
-        return hasBackgroundImage();
+        return hasBackgroundImage() || hasBackdropFilter();

[pdr., 2015/09/04 22:42:13]

I think we need to return hasBackdropFilter from
hasBoxDecorationsOrBackgroundImage and maybe rename it?

BoxDecorationData also looks like it needs a hasBackdropFilter().

Basically, just search cs.chromium.org for hasBackgroundImage().

It would be great if we could test some of these places just to make sure we're
doing the right thing.

     }
 
     LayoutRectOutsets imageOutsets(const NinePieceImage&) const;