Clear the custom element's reaction queue if upgrade fails.

third_party/WebKit/Source/core/dom/custom/CustomElementReactionStack.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/dom/custom/CustomElementReactionStack.h"
 
 #include "bindings/core/v8/Microtask.h"
 #include "core/dom/Element.h"
 #include "core/dom/custom/CEReactionsScope.h"
 #include "core/dom/custom/CustomElementReactionQueue.h"
 #include "core/frame/FrameHost.h"
 
 namespace blink {
 
 namespace {
 
-CustomElementReactionStack& customElementReactionStack() {
-  DEFINE_STATIC_LOCAL(CustomElementReactionStack, customElementReactionStack,
+Persistent<CustomElementReactionStack>& customElementReactionStack() {
+  DEFINE_STATIC_LOCAL(Persistent<CustomElementReactionStack>,
+                      customElementReactionStack,
                       (new CustomElementReactionStack));
   return customElementReactionStack;
 }
 
 }  // namespace
 
 // TODO(dominicc): Consider using linked heap structures, avoiding
 // finalizers, to make short-lived entries fast.
 
 CustomElementReactionStack::CustomElementReactionStack() {}
@@ skipping 60 matching lines @@
   // If the processing the backup element queue is not set:
   if (!m_backupQueue || m_backupQueue->isEmpty()) {
     Microtask::enqueueMicrotask(
         WTF::bind(&CustomElementReactionStack::invokeBackupQueue,
                   Persistent<CustomElementReactionStack>(this)));
   }
 
   enqueue(m_backupQueue, element, reaction);
 }
 
+void CustomElementReactionStack::clearQueue(Element* element) {
+  if (CustomElementReactionQueue* reactions = m_map.get(element))
+    reactions->clear();
+}
+
 void CustomElementReactionStack::invokeBackupQueue() {
   DCHECK(isMainThread());
   invokeReactions(*m_backupQueue);
   m_backupQueue->clear();
 }
 
 CustomElementReactionStack& CustomElementReactionStack::current() {
-  return customElementReactionStack();
+  return *customElementReactionStack();
+}
+
+CustomElementReactionStack*
+CustomElementReactionStackTestSupport::setCurrentForTest(
+    CustomElementReactionStack* newStack) {
+  Persistent<CustomElementReactionStack>& stack = customElementReactionStack();
+  CustomElementReactionStack* oldStack = stack.get();
+  stack = newStack;
+  return oldStack;
 }
 
 }  // namespace blink