Add Blink support for showing image placeholders using range requests.

third_party/WebKit/Source/core/page/DragController.cpp

 /*
  * Copyright (C) 2007, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 51 matching lines @@
 #include "core/layout/LayoutTheme.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/loader/FrameLoadRequest.h"
 #include "core/loader/FrameLoader.h"
 #include "core/page/ChromeClient.h"
 #include "core/page/DragData.h"
 #include "core/page/DragSession.h"
 #include "core/page/DragState.h"
 #include "core/page/Page.h"
 #include "platform/DragImage.h"
+#include "platform/SharedBuffer.h"
 #include "platform/geometry/IntRect.h"
 #include "platform/geometry/IntSize.h"
 #include "platform/graphics/BitmapImage.h"
 #include "platform/graphics/Image.h"
 #include "platform/graphics/ImageOrientation.h"
 #include "platform/network/ResourceRequest.h"
 #include "platform/weborigin/SecurityOrigin.h"
 #include "public/platform/WebCommon.h"
 #include "public/platform/WebDragData.h"
 #include "public/platform/WebDragOperation.h"
 #include "public/platform/WebImage.h"
 #include "public/platform/WebPoint.h"
 #include "public/platform/WebScreenInfo.h"
 #include "wtf/Assertions.h"
 #include "wtf/CurrentTime.h"
+#include "wtf/PassRefPtr.h"
 #include "wtf/RefPtr.h"
 #include <memory>
 
 #if OS(WIN)
 #include <windows.h>
 #endif
 
 namespace blink {
 
 static const int MaxOriginalImageArea = 1500 * 1500;
@@ skipping 982 matching lines @@
       dragImage = src->dragImageForSelection(DragImageAlpha);
       dragLocation = dragLocationForSelectionDrag(src);
     }
     doSystemDrag(dragImage.get(), dragLocation, dragOrigin, dataTransfer, src,
                  false);
   } else if (state.m_dragType == DragSourceActionImage) {
     if (imageURL.isEmpty() || !node || !node->isElementNode())
       return false;
     Element* element = toElement(node);
     Image* image = getImage(element);
-    if (!image || image->isNull())
+    if (!image || image->isNull() || !image->data() || !image->data()->size())
       return false;
     // We shouldn't be starting a drag for an image that can't provide an
     // extension.
     // This is an early detection for problems encountered later upon drop.
     DCHECK(!image->filenameExtension().isEmpty());
     if (!dragImage) {
       const IntRect& imageRect = hitTestResult.imageRect();
       IntSize imageSizeInPixels = imageRect.size();
       // TODO(oshima): Remove this scaling and simply pass imageRect to
       // dragImageForImage
@@ skipping 111 matching lines @@
 }
 
 DEFINE_TRACE(DragController) {
   visitor->trace(m_page);
   visitor->trace(m_documentUnderMouse);
   visitor->trace(m_dragInitiator);
   visitor->trace(m_fileInputElementUnderMouse);
 }
 
 }  // namespace blink