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

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

 // 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.
 
 #include "core/paint/SVGClipPainter.h"
 
 #include "core/dom/ElementTraversal.h"
 #include "core/layout/svg/LayoutSVGResourceClipper.h"
 #include "core/layout/svg/SVGLayoutSupport.h"
 #include "core/layout/svg/SVGResources.h"
@@ skipping 109 matching lines @@
         {
             AffineTransform contentTransform;
             if (m_clip.clipPathUnits() == SVGUnitTypes::SVG_UNIT_TYPE_OBJECTBOUNDINGBOX) {
                 contentTransform.translate(targetBoundingBox.x(), targetBoundingBox.y());
                 contentTransform.scaleNonUniform(targetBoundingBox.width(), targetBoundingBox.height());
             }
             SubtreeContentTransformScope contentTransformScope(contentTransform);
 
             TransformRecorder contentTransformRecorder(maskContext, layoutObject, contentTransform);
             RefPtr<const SkPicture> clipContentPicture = m_clip.createContentPicture();
-            maskContext.getPaintController().createAndAppend<DrawingDisplayItem>(layoutObject, DisplayItem::SVGClip, clipContentPicture.get());
+            if (clipContentPicture)
+                maskContext.getPaintController().createAndAppend<DrawingDisplayItem>(layoutObject, DisplayItem::SVGClip, clipContentPicture.get());
         }
 
         if (clipPathClipper)
             SVGClipPainter(*clipPathClipper).finishEffect(m_clip, maskContext, clipPathClipperState);
     }
 
     LayoutObjectDrawingRecorder drawingRecorder(context, layoutObject, DisplayItem::SVGClip, targetPaintInvalidationRect);
     RefPtr<SkPicture> maskPicture = maskPictureBuilder.endRecording();
-    context.drawPicture(maskPicture.get());
+    if (maskPicture)
+        context.drawPicture(maskPicture.get());
     return true;
 }
 
 } // namespace blink