Ensure display items are unique when multiple nested clip paths are used

third_party/WebKit/Source/core/paint/SVGClipPainter.h

 // Copyright 2015 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.
 
 #ifndef SVGClipPainter_h
 #define SVGClipPainter_h
 
 #include "platform/geometry/FloatRect.h"
 #include "platform/graphics/paint/DisplayItemClient.h"
 #include "wtf/Allocator.h"
 
 namespace blink {
 
+class AffineTransform;
 class GraphicsContext;
 class LayoutObject;
 class LayoutSVGResourceClipper;
 
 class SVGClipPainter {
     STACK_ALLOCATED();
 public:
     enum ClipperState {
         ClipperNotApplied,
         ClipperAppliedPath,
         ClipperAppliedMask
     };
 
     SVGClipPainter(LayoutSVGResourceClipper& clip) : m_clip(clip) { }
 
     // FIXME: Filters are also stateful resources that could benefit from having their state managed
     //        on the caller stack instead of the current hashmap. We should look at refactoring these
     //        into a general interface that can be shared.
     bool prepareEffect(const LayoutObject&, const FloatRect&, const FloatRect&, GraphicsContext&, ClipperState&);
     void finishEffect(const LayoutObject&, GraphicsContext&, ClipperState&);
 
 private:
-    void drawClipMaskContent(GraphicsContext&, const LayoutObject&, const FloatRect& targetBoundingBox, const FloatRect& targetPaintInvalidationRect);
+    // Return false if there is a problem drawing the mask.
+    bool drawClipAsMask(GraphicsContext&, const LayoutObject&, const FloatRect& targetBoundingBox, const FloatRect& targetPaintInvalidationRect, const AffineTransform&);
 
     LayoutSVGResourceClipper& m_clip;
 };
 
 } // namespace blink
 
 #endif // SVGClipPainter_h