Fire load event for an image even if it was the last image we loaded successfully.

Source/core/loader/ImageLoader.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010 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 271 matching lines @@
         }
     } else {
         if (!imageSourceURL.isNull()) {
             // Fire an error event if the url string is not empty, but the KURL is.
             dispatchErrorEvent();
         }
         noImageResourceToLoad();
     }
 
     ImageResource* oldImage = m_image.get();
-    if (newImage != oldImage) {
-        sourceImageChanged();
+    if (updateBehavior == UpdateSizeChanged && m_element->layoutObject() && m_element->layoutObject()->isImage() && newImage == oldImage) {

[Yoav Weiss, 2015/04/02 07:52:10]

Hmm, I'm not sure that's the cleanest way to do that. The UpdateSizeChanged
behavior is there to update the image intrinsic size as a result of environment
changes. If that triggers onload in your test cases, I suspect it's a
side-effect :|

[rhogan, 2015/04/02 18:15:16]

It's not material for the test cases added by my CL, but there is coverage in
LayoutTests for the case where the viewport changes and srcset resizes the image
but doesn't select a new one. In that situation the spec tells me I don't want
to trigger a load event so that's what I'm doing here. 

+        toLayoutImage(m_element->layoutObject())->intrinsicSizeChanged();
+    } else {
+        if (newImage != oldImage)
+            sourceImageChanged();
 
         if (m_hasPendingLoadEvent) {
             loadEventSender().cancelEvent(this);
             m_hasPendingLoadEvent = false;
         }
 
         // Cancel error events that belong to the previous load, which is now cancelled by changing the src attribute.
         // If newImage is null and m_hasPendingErrorEvent is true, we know the error event has been just posted by
         // this load and we should not cancel the event.
         // FIXME: If both previous load and this one got blocked with an error, we can receive one error event instead of two.
         if (m_hasPendingErrorEvent && newImage) {
             errorEventSender().cancelEvent(this);
             m_hasPendingErrorEvent = false;
         }
 
         m_image = newImage;
         m_hasPendingLoadEvent = newImage;
         m_imageComplete = !newImage;
 
         updateRenderer();
         // If newImage exists and is cached, addClient() will result in the load event
         // being queued to fire. Ensure this happens after beforeload is dispatched.
         if (newImage)
             newImage->addClient(this);
 
         if (oldImage)
             oldImage->removeClient(this);

[Jimmy Jo, 2016/04/28 13:02:33]

I have a question.
If newImage and oldImage are equal, is this line same
newImage->removeClient(this)?

-    } else if (updateBehavior == UpdateSizeChanged && m_element->layoutObject() && m_element->layoutObject()->isImage()) {
-        toLayoutImage(m_element->layoutObject())->intrinsicSizeChanged();
     }
 
     if (LayoutImageResource* imageResource = layoutImageResource())
         imageResource->resetAnimation();
 
     // Only consider updating the protection ref-count of the Element immediately before returning
     // from this function as doing so might result in the destruction of this ImageLoader.
     updatedHasPendingEvent();
 }
 
@@ skipping 261 matching lines @@
 #endif
 }
 
 #if ENABLE(OILPAN)
 ImageLoader::ImageLoaderClientRemover::~ImageLoaderClientRemover()
 {
     m_loader.willRemoveClient(m_client);
 }
 #endif
 }