Blink: Throttle progressively loaded images.

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 11 matching lines @@
 
 #ifndef ImageResource_h
 #define ImageResource_h
 
 #include "core/CoreExport.h"
 #include "core/fetch/MultipartImageResourceParser.h"
 #include "core/fetch/Resource.h"
 #include "platform/geometry/IntRect.h"
 #include "platform/geometry/IntSizeHash.h"
 #include "platform/geometry/LayoutSize.h"
+#include "platform/graphics/Image.h"
 #include "platform/graphics/ImageObserver.h"
 #include "platform/graphics/ImageOrientation.h"
 #include "wtf/HashMap.h"
 #include <memory>
 
 namespace blink {
 
 class FetchRequest;
 class ImageResourceObserver;
 class MemoryCache;
@@ skipping 151 matching lines @@
 
   void checkNotify() override;
   void notifyObserversInternal(MarkFinishedOption);
   void markObserverFinished(ImageResourceObserver*);
 
   void doResetAnimation();
 
   void destroyDecodedDataIfPossible() override;
   void destroyDecodedDataForFailedRevalidation() override;
 
+  void flushImageIfNeeded(TimerBase*);
+
   float m_devicePixelRatioHeaderValue;
 
   Member<MultipartImageResourceParser> m_multipartParser;
   RefPtr<blink::Image> m_image;
   MultipartParsingState m_multipartParsingState =
       MultipartParsingState::WaitingForFirstPart;
   bool m_hasDevicePixelRatioHeaderValue;
   HashCountedSet<ImageResourceObserver*> m_observers;
   HashCountedSet<ImageResourceObserver*> m_finishedObservers;
 
   // 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.
   bool m_isPlaceholder;
+
+  Timer<ImageResource> m_flushTimer;
+  double m_lastFlushTime = 0.;
+  Image::SizeAvailability m_sizeAvailable = Image::SizeUnavailable;
 };
 
 DEFINE_RESOURCE_TYPE_CASTS(Image);
 
 }  // namespace blink
 
 #endif