blink: Add backdrop-filter support

Source/core/layout/compositing/CompositingReasonFinder.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/layout/compositing/CompositingReasonFinder.h"
 
 #include "core/CSSPropertyNames.h"
 #include "core/dom/Document.h"
 #include "core/frame/FrameView.h"
@@ skipping 94 matching lines @@
 
     // If the implementation of createsGroup changes, we need to be aware of that in this part of code.
     ASSERT((layoutObject->isTransparent() || layoutObject->hasMask() || layoutObject->hasFilter() || style.hasBlendMode()) == layoutObject->createsGroup());
 
     if (style.hasMask())
         reasons |= CompositingReasonMaskWithCompositedDescendants;
 
     if (style.hasFilter())
         reasons |= CompositingReasonFilterWithCompositedDescendants;
 
+    if (style.hasBackdropFilter())
+        reasons |= CompositingReasonBackdropFilter;
+
     // See Layer::updateTransform for an explanation of why we check both.
     if (layoutObject->hasTransformRelatedProperty() && style.hasTransform())
         reasons |= CompositingReasonTransformWithCompositedDescendants;
 
     if (layoutObject->isTransparent())
         reasons |= CompositingReasonOpacityWithCompositedDescendants;
 
     if (style.hasBlendMode())
         reasons |= CompositingReasonBlendingWithCompositedDescendants;
 
@@ skipping 52 matching lines @@
 bool CompositingReasonFinder::requiresCompositingForPositionFixed(const DeprecatedPaintLayer* layer) const
 {
     if (!(m_compositingTriggers & ViewportConstrainedPositionedTrigger))
         return false;
     // Don't promote fixed position elements that are descendants of a non-view container, e.g. transformed elements.
     // They will stay fixed wrt the container rather than the enclosing frame.
     return layer->scrollsWithViewport() && m_layoutView.frameView()->isScrollable();
 }
 
 }