Show image placeholders on dimension decode error

third_party/WebKit/Source/core/loader/resource/ImageResource.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. 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.
@@ skipping 142 matching lines @@
   // Indicates if the ImageResource is currently scheduling a reload, e.g.
   // because reloadIfLoFi() was called.
   bool m_isSchedulingReload;
 
   // Indicates if this ImageResource is either attempting to load a placeholder
   // image, or is a (possibly broken) placeholder image.
   enum class PlaceholderOption {
     // Do not show or reload placeholder.
     DoNotReloadPlaceholder,
 
+    // Show placeholder, and do not reload.

[sclittle, 2017/04/06 21:58:06]

nit: could you clarify in the comment here that the original image will still be
loaded and shown if the image is explicitly reloaded, e.g. when
reloadIfLoFiOrPlaceholderImage is called with kReloadAlways?

+    ShowAndDoNotReloadPlaceholder,
+
     // Do not show placeholder, reload only when decode error occurs.
     ReloadPlaceholderOnDecodeError,
 
     // Show placeholder and reload.
     ShowAndReloadPlaceholderAlways,
   };
   PlaceholderOption m_placeholderOption;
 
   Timer<ImageResource> m_flushTimer;
   double m_lastFlushTime = 0.;
 };
 
 DEFINE_RESOURCE_TYPE_CASTS(Image);
 
 }  // namespace blink
 
 #endif