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

third_party/WebKit/Source/web/WebLocalFrameImpl.cpp

 /*
  * Copyright (C) 2009 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 294 matching lines @@
 
         frame()->view()->updateAllLifecyclePhases();
         if (!frame()->document() || !frame()->document()->layoutView())
             return 0;
 
         IntRect pageRect = m_pageRects[pageNumber];
         SkPictureBuilder pictureBuilder(pageRect, &skia::GetMetaData(*canvas));
         pictureBuilder.context().setPrinting(true);
 
         float scale = spoolPage(pictureBuilder.context(), pageNumber);
-        pictureBuilder.endRecording()->playback(canvas);
+        RefPtr<const SkPicture> recording = pictureBuilder.endRecording();
+        if (recording)
+            recording->playback(canvas);
         return scale;
     }
 
     void spoolAllPagesWithBoundaries(WebCanvas* canvas, const FloatSize& pageSizeInPixels)
     {
         dispatchEventsForPrintingOnAllFrames();
         if (!frame()->document() || !frame()->document()->layoutView())
             return;
 
         frame()->view()->updateAllLifecyclePhases();
@@ skipping 38 matching lines @@
             // Account for the disabling of scaling in spoolPage. In the context
             // of spoolAllPagesWithBoundaries the scale HAS NOT been pre-applied.
             float scale = getPageShrink(pageIndex);
             transform.scale(scale, scale);
 #endif
             TransformRecorder transformRecorder(context, *this, transform);
             spoolPage(context, pageIndex);
 
             currentHeight += pageSizeInPixels.height() + 1;
         }
-        pictureBuilder.endRecording()->playback(canvas);
+        RefPtr<const SkPicture> recording = pictureBuilder.endRecording();
+        if (recording)
+            recording->playback(canvas);
     }
 
     // DisplayItemClient methods
     String debugName() const final { return "ChromePrintContext"; }
     LayoutRect visualRect() const override { return LayoutRect(); }
 
 protected:
     // Spools the printed page, a subrect of frame(). Skip the scale step.
     // NativeTheme doesn't play well with scaling. Scaling is done browser side
     // instead. Returns the scale to be applied.
@@ skipping 1804 matching lines @@
         return WebSandboxFlags::None;
     return static_cast<WebSandboxFlags>(frame()->loader().effectiveSandboxFlags());
 }
 
 void WebLocalFrameImpl::forceSandboxFlags(WebSandboxFlags flags)
 {
     frame()->loader().forceSandboxFlags(static_cast<SandboxFlags>(flags));
 }
 
 } // namespace blink