blink: Add backdrop-filter support

Source/platform/graphics/GraphicsLayer.h

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 158 matching lines @@
     void setBackfaceVisibility(bool visible);
 
     float opacity() const { return m_opacity; }
     void setOpacity(float);
 
     void setBlendMode(WebBlendMode);
     void setScrollBlocksOn(WebScrollBlocksOn);
     void setIsRootForIsolatedGroup(bool);
 
     void setFilters(const FilterOperations&);
+    void setBackdropFilters(const FilterOperations&);
 
     void setFilterQuality(SkFilterQuality);
 
     // Some GraphicsLayers paint only the foreground or the background content
     void setPaintingPhase(GraphicsLayerPaintingPhase);
 
     void setNeedsDisplay();
     // Mark the given rect (in layer coords) as needing display. Never goes deep.
     void setNeedsDisplayInRect(const IntRect&, PaintInvalidationReason);
 
@@ skipping 171 matching lines @@
 };
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the blink namespace for ease of invocation from gdb.
 void PLATFORM_EXPORT showGraphicsLayerTree(const blink::GraphicsLayer*);
 #endif
 
 #endif // GraphicsLayer_h