Explicitly clear the image in the first updateImage() call

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.
 
     This library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Library General Public License for more details.
 
     You should have received a copy of the GNU Library General Public License
     along with this library; see the file COPYING.LIB.  If not, write to
     the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     Boston, MA 02110-1301, USA.
 */
 
 #ifndef ImageResource_h
 #define ImageResource_h
 
 #include "core/CoreExport.h"
+#include "core/fetch/ImageResourceContent.h"

[hajimehoshi, 2016/12/06 07:26:00]

I couldn't find this file.

 #include "core/fetch/MultipartImageResourceParser.h"
 #include "core/fetch/Resource.h"
 #include <memory>
 
 namespace blink {
 
 class FetchRequest;
 class ResourceClient;
 class ResourceFetcher;
 class SecurityOrigin;
-class ImageResourceContent;
 
 // ImageResource is the resource-related part of image loading.
 // Image-related things (blink::Image and ImageResourceObserver) are handled by
 // ImageResourceContent.
 // Most users should use ImageResourceContent instead of ImageResource.
 // https://docs.google.com/document/d/1O-fB83mrE0B_V8gzXNqHgmRLCvstTB4MMi3RnVLr8bE/edit?usp=sharing
 //
 // As for the lifetimes of ImageResourceContent::m_image and m_data, see this
 // document:
 // https://docs.google.com/document/d/1v0yTAZ6wkqX2U_M6BNIGUJpM1s0TIw1VsqpxoL7aciY/edit?usp=sharing
@@ skipping 80 matching lines @@
 
   bool hasClientsOrObservers() const override;
 
   void updateImageAndClearBuffer();
 
   void checkNotify() override;
 
   void destroyDecodedDataIfPossible() override;
   void destroyDecodedDataForFailedRevalidation() override;
 
+  // When ClearImageOption is KeepExistingImage but this is the first
+  // updateImage() call, then ClearExistingImage is used instead to enforce
+  // new image creation.
+  void updateImage(PassRefPtr<SharedBuffer>,
+                   ImageResourceContent::ClearImageOption,
+                   bool allDataReceived);
   void flushImageIfNeeded(TimerBase*);
 
   bool willPaintBrokenImage() const;
 
   Member<ImageResourceContent> m_content;
 
+  // Indicates whether updateImage() is called for this resource, or for this
+  // part (in case of multipart images), and is used for enforcing creation of
+  // new blink::Image in ImageResourceContent for the first updateImage().
+  bool m_isUpdateImageCalled = false;
+
   float m_devicePixelRatioHeaderValue;
 
   Member<MultipartImageResourceParser> m_multipartParser;
   MultipartParsingState m_multipartParsingState =
       MultipartParsingState::WaitingForFirstPart;
   bool m_hasDevicePixelRatioHeaderValue;
 
   // 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.;
 };
 
 DEFINE_RESOURCE_TYPE_CASTS(Image);
 
 }  // namespace blink
 
 #endif