Update comments regarding image caching

third_party/WebKit/Source/core/fetch/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 42 matching lines @@
     ImageResource(blink::Image*);
     // Exposed for testing
     ImageResource(const ResourceRequest&, blink::Image*);
     ~ImageResource() override;
 
     void load(ResourceFetcher*, const ResourceLoaderOptions&) override;
 
     blink::Image* image(); // Returns the nullImage() if the image is not available yet.
     bool hasImage() const { return m_image.get(); }
     // Side effect: ensures decoded image is in cache, therefore should only be called when about to draw the image.
-    // FIXME: Decoding image on the main thread is expensive, so rather than forcing decode, consider returning false
-    // when image is not decoded yet, as we do in case of deferred decoding.
     bool currentFrameKnownToBeOpaque(const LayoutObject*);
 
     static std::pair<blink::Image*, float> brokenImage(float deviceScaleFactor); // Returns an image and the image's resolution scale factor.
     bool willPaintBrokenImage() const;
 
     // Assumes that image rotation or scale doesn't effect the image size being empty or not.
     bool canRender() { return !errorOccurred() && !imageSizeForLayoutObject(nullptr, 1).isEmpty(); }
 
     bool usesImageContainerSize() const;
     bool imageHasRelativeWidth() const;
@@ skipping 70 matching lines @@
 
     RefPtr<blink::Image> m_image;
     bool m_hasDevicePixelRatioHeaderValue;
 };
 
 DEFINE_RESOURCE_TYPE_CASTS(Image);
 
 }
 
 #endif