Partial reland of "Add CHECK()s about ImageLoader::has_pending_load_event_"

third_party/WebKit/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 501 matching lines @@
 }
 
 void ImageLoader::ImageNotifyFinished(ImageResourceContent* resource) {
   RESOURCE_LOADING_DVLOG(1)
       << "ImageLoader::imageNotifyFinished " << this
       << "; has_pending_load_event_=" << has_pending_load_event_;
 
   DCHECK(failed_load_url_.IsEmpty());
   DCHECK_EQ(resource, image_.Get());
 
+  // |has_pending_load_event_| is always false and |image_complete_| is
+  // always true for entire ImageDocument loading for historical reason.
+  // DoUpdateFromElement() is not called and SetImageForImageDocument()
+  // is called instead for ImageDocument loading.
+  // TODO(hiroshige): Turn the CHECK()s to DCHECK()s before going to beta.
+  if (loading_image_document_)
+    CHECK(image_complete_);
+  else
+    CHECK(!image_complete_);
+
   image_complete_ = true;
 
   // Update ImageAnimationPolicy for image_.
   if (image_)
     image_->UpdateImageAnimationPolicy();
 
   UpdateLayoutObject();
 
   if (image_ && image_->GetImage() && image_->GetImage()->IsSVGImage())
     ToSVGImage(image_->GetImage())
         ->UpdateUseCounters(GetElement()->GetDocument());
 
-  if (!has_pending_load_event_)
+  if (loading_image_document_) {
+    CHECK(!has_pending_load_event_);
     return;
+  }
+
+  CHECK(has_pending_load_event_);
 
   if (resource->ErrorOccurred()) {
     LoadEventSender().CancelEvent(this);
     has_pending_load_event_ = false;
 
     if (resource->GetResourceError().IsAccessCheck()) {
       CrossSiteOrCSPViolationOccurred(
           AtomicString(resource->GetResourceError().FailingURL()));
     }
 
@@ skipping 79 matching lines @@
   DCHECK(event_sender == &LoadEventSender() ||
          event_sender == &ErrorEventSender());
   const AtomicString& event_type = event_sender->EventType();
   if (event_type == EventTypeNames::load)
     DispatchPendingLoadEvent();
   if (event_type == EventTypeNames::error)
     DispatchPendingErrorEvent();
 }
 
 void ImageLoader::DispatchPendingLoadEvent() {
-  if (!has_pending_load_event_)
-    return;
+  CHECK(has_pending_load_event_);
   if (!image_)
     return;
+  CHECK(image_complete_);
   has_pending_load_event_ = false;
   if (GetElement()->GetDocument().GetFrame())
     DispatchLoadEvent();
 
   // 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();
 }
 
 void ImageLoader::DispatchPendingErrorEvent() {
+  // Currently this if condition is needed because there can be multiple
+  // in-flight error event tasks and we process only the first here.

[kinuko, 2017/05/15 20:12:50]

whoa..

+  // crbug.com/722500
+  // TODO(hiroshige): Replace this with |CHECK(has_pending_load_event_)|.
   if (!has_pending_error_event_)
     return;
   has_pending_error_event_ = false;
 
   if (GetElement()->GetDocument().GetFrame())
     GetElement()->DispatchEvent(Event::Create(EventTypeNames::error));
 
   // 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.
@@ skipping 17 matching lines @@
 }
 
 void ImageLoader::ElementDidMoveToNewDocument() {
   if (load_delay_counter_)
     load_delay_counter_->DocumentChanged(element_->GetDocument());
   ClearFailedLoadURL();
   ClearImage();
 }
 
 }  // namespace blink