Deal gracefully with null {GraphicsContext,SkPictureBuilder}.endRecording() results.

third_party/WebKit/Source/core/layout/svg/LayoutSVGResourceClipper.h

 /*
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  *
  * 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
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 29 matching lines @@
     FloatRect resourceBoundingBox(const LayoutObject*);
 
     static const LayoutSVGResourceType s_resourceType = ClipperResourceType;
     LayoutSVGResourceType resourceType() const override { return s_resourceType; }
 
     bool hitTestClipContent(const FloatRect&, const FloatPoint&);
 
     SVGUnitTypes::SVGUnitType clipPathUnits() const { return toSVGClipPathElement(element())->clipPathUnits()->currentValue()->enumValue(); }
 
     bool asPath(const AffineTransform&, const FloatRect& referenceBox, Path&);
+    // Returns a picture to paint the contents of the resource, or nullptr if the picture couldn't be created.

[chrishtr, 2016/03/29 22:42:23]

Add a sentence that the second scenario should only happen in testing.

[wkorman, 2016/03/29 22:52:02]

Done.

     PassRefPtr<const SkPicture> createContentPicture();
 
     bool hasCycle() { return m_inClipExpansion; }
     void beginClipExpansion() { ASSERT(!m_inClipExpansion); m_inClipExpansion = true; }
     void endClipExpansion() { ASSERT(m_inClipExpansion); m_inClipExpansion = false; }
 private:
     void calculateClipContentPaintInvalidationRect();
 
     // Return true if the clip path was calculated or a cached value is available.
     bool calculateClipContentPathIfNeeded();
 
     // Cache of the clip path when using path clipping.
     Path m_clipContentPath;
 
     // Cache of the clip path picture when falling back to masking for clipping.
     RefPtr<const SkPicture> m_clipContentPicture;
 
     FloatRect m_clipBoundaries;
 
     // Reference cycle detection.
     bool m_inClipExpansion;
 };
 
 DEFINE_LAYOUT_SVG_RESOURCE_TYPE_CASTS(LayoutSVGResourceClipper, ClipperResourceType);
 
 } // namespace blink
 
 #endif