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

third_party/WebKit/Source/platform/graphics/GeneratedImage.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 30 matching lines @@
     const FloatPoint& phase, SkXfermode::Mode compositeOp, const FloatRect& destRect,
     const FloatSize& repeatSpacing)
 {
     FloatRect tileRect = srcRect;
     tileRect.expand(FloatSize(repeatSpacing));
 
     SkPictureBuilder builder(tileRect, nullptr, &destContext);
     builder.context().beginRecording(tileRect);
     drawTile(builder.context(), srcRect);
     RefPtr<SkPicture> tilePicture = builder.endRecording();
+    if (!tilePicture)
+        return;
 
     AffineTransform patternTransform;
     patternTransform.translate(phase.x(), phase.y());
     patternTransform.scale(scale.width(), scale.height());
     patternTransform.translate(tileRect.x(), tileRect.y());
 
     RefPtr<Pattern> picturePattern = Pattern::createPicturePattern(tilePicture.release());
     picturePattern->setPatternSpaceTransform(patternTransform);
 
     SkPaint fillPaint = destContext.fillPaint();
     picturePattern->applyToPaint(fillPaint);
     fillPaint.setColor(SK_ColorBLACK);
     fillPaint.setXfermodeMode(compositeOp);
 
     destContext.drawRect(destRect, fillPaint);
 }
 
 PassRefPtr<SkImage> GeneratedImage::imageForCurrentFrame()
 {
     return nullptr;
 }
 
 } // namespace blink