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

third_party/WebKit/Source/core/frame/LocalFrame.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Simon Hausmann <hausmann@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  *                     2001 George Staikos <staikos@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov <ap@nypop.com>
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 109 matching lines @@
     }
 
     GraphicsContext& context() { return m_pictureBuilder->context(); }
 
     PassOwnPtr<DragImage> createImage()
     {
         if (m_draggedNode && m_draggedNode->layoutObject())
             m_draggedNode->layoutObject()->updateDragState(false);
         context().getPaintController().endItem<EndTransformDisplayItem>(*m_localFrame);
         RefPtr<const SkPicture> recording = m_pictureBuilder->endRecording();
+        if (!recording)

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

Did you check call sites to be robust aginst nullptr?

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

Yes.

+            return nullptr;
+
         RefPtr<SkImage> skImage = adoptRef(SkImage::NewFromPicture(recording.get(),
             SkISize::Make(m_bounds.width(), m_bounds.height()), nullptr, nullptr));
         RefPtr<Image> image = StaticBitmapImage::create(skImage.release());
         RespectImageOrientationEnum imageOrientation = DoNotRespectImageOrientation;
         if (m_draggedNode && m_draggedNode->layoutObject())
             imageOrientation = LayoutObject::shouldRespectImageOrientation(m_draggedNode->layoutObject());
 
         float screenDeviceScaleFactor = m_localFrame->page()->chromeClient().screenInfo().deviceScaleFactor;
 
         return DragImage::create(image.get(), imageOrientation, screenDeviceScaleFactor, InterpolationHigh, m_opacity);
@@ skipping 735 matching lines @@
 {
     m_frame->disableNavigation();
 }
 
 FrameNavigationDisabler::~FrameNavigationDisabler()
 {
     m_frame->enableNavigation();
 }
 
 } // namespace blink