Change the semantics of ImageLoader::has_pending_load_event_

third_party/WebKit/Source/core/loader/ImageLoader.cpp

Index: third_party/WebKit/Source/core/loader/ImageLoader.cpp
diff --git a/third_party/WebKit/Source/core/loader/ImageLoader.cpp b/third_party/WebKit/Source/core/loader/ImageLoader.cpp
index efb2bde0845ca1dad5712bc41534ff1f914726d1..49a8cfbfddf11320a29348b0d5cda3ecb3e3342e 100644
--- a/third_party/WebKit/Source/core/loader/ImageLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/ImageLoader.cpp
@@ -359,7 +359,6 @@ void ImageLoader::DoUpdateFromElement(BypassMainWorldBehavior bypass_behavior,
     }
 
     image_ = new_image;
-    has_pending_load_event_ = new_image;
     image_complete_ = !new_image;
     delay_until_image_notify_finished_ = nullptr;
 

[hiroshige, 2017/05/05 19:58:31]

Previous: has_pending_load_event_ == true iff new_image is non-null.

Now: if new_image is non-null,
  (image_ && !image_complete_) || has_pending_load_event_ == true:
    has_pending_load_event_ == false
    image_complete_ == false
    image_ != null

  otherwise,
  (image_ && !image_complete_) || has_pending_load_event_ == false:
    has_pending_load_event_ == false
    image_complete_ == true
    image == null

@@ -515,12 +514,8 @@ void ImageLoader::ImageNotifyFinished(ImageResourceContent* resource) {
     ToSVGImage(image_->GetImage())
         ->UpdateUseCounters(GetElement()->GetDocument());
 
-  if (loading_image_document_) {
-    CHECK(!has_pending_load_event_);
+  if (loading_image_document_)
     return;
-  }
-
-  CHECK(has_pending_load_event_);

[hiroshige, 2017/05/05 19:58:31]

Previous: We assert has_pending_load_event_ == true.

Now: This means
     (image_ && !image_complete_) || has_pending_load_event_ == true,
     at the beginning of ImageNotifyFinished().
     image_ is non-null (as ImageNotifyFinished() is called),
     image_complete_ is false (asserted at Line 502)
     therefore this assert always holds and I removed this CHECK().
     (actually has_pending_load_event_ is expected to be false)

 
   if (resource->ErrorOccurred()) {
     LoadEventSender().CancelEvent(this);
@@ -543,6 +538,7 @@ void ImageLoader::ImageNotifyFinished(ImageResourceContent* resource) {
     UpdatedHasPendingEvent();
     return;
   }
+  has_pending_load_event_ = true;
   LoadEventSender().DispatchEventSoon(this);
 }
 
@@ -589,7 +585,8 @@ void ImageLoader::UpdatedHasPendingEvent() {
   // such an Element wishes for the load to stop when removed from the DOM it
   // needs to stop the ImageLoader explicitly.
   bool was_protected = element_is_protected_;
-  element_is_protected_ = has_pending_load_event_ || has_pending_error_event_;
+  element_is_protected_ = (image_ && !image_complete_) ||
+                          has_pending_load_event_ || has_pending_error_event_;
   if (was_protected == element_is_protected_)
     return;
 
@@ -625,6 +622,7 @@ void ImageLoader::DispatchPendingLoadEvent() {
     return;
   CHECK(image_complete_);
   has_pending_load_event_ = false;
+  CHECK(image_complete_);
   if (GetElement()->GetDocument().GetFrame())
     DispatchLoadEvent();