Make custom elements work in HTML imports

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

Index: third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp
diff --git a/third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp b/third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp
index 6ecc7a8ea89b49ab40328c7981fe22f933eed729..5f6dcbb7e98035dbb37321553b9ba85deaa652b2 100644
--- a/third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.cpp
@@ -79,6 +79,9 @@ CustomElementsRegistry::CustomElementsRegistry(const LocalDOMWindow* owner)
     , m_v0 (new V0RegistrySet())
     , m_upgradeCandidates(new UpgradeCandidateMap())
 {
+    // !contextDocument() just for unit testing.
+    DCHECK(m_owner->document() == m_owner->document()->contextDocument()
+        || !m_owner->document()->contextDocument());
 }
 
 DEFINE_TRACE(CustomElementsRegistry)
@@ -234,6 +237,10 @@ CustomElementDefinition* CustomElementsRegistry::definitionForName(
 
 void CustomElementsRegistry::addCandidate(Element* candidate)
 {
+    // !contextDocument() just for unit testing.
+    DCHECK(candidate->document().contextDocument() == m_owner->document()
+        || !candidate->document().contextDocument());
+
     const AtomicString& name = candidate->localName();
     if (nameIsDefined(name) || v0NameIsDefined(name))
         return;
@@ -269,6 +276,33 @@ ScriptPromise CustomElementsRegistry::whenDefined(
     return newResolver->promise();
 }
 
+using ElementsInDocument = HeapVector<Member<Element>>;
+using ElementsDocumentMap = HeapHashMap<Document*, ElementsInDocument>;
+
+static void addToImports(ElementsDocumentMap& imports, Element* element)
+{
+    Document* document = &element->document();
+    const auto& it = imports.find(document);
+    ElementsInDocument* list;
+    if (it != imports.end()) {
+        list = &it->value;
+    } else {
+        list = &imports.add(document, ElementsInDocument())
+            .storedValue->value;
+    }
+    list->append(element);
+}
+
+static void collectFromImports(ElementsDocumentMap& imports, HeapVector<Member<Element>>* elements)
+{
+    for (const auto& it : imports) {
+        CustomElementUpgradeSorter sorter;
+        for (Element* element : it.value)
+            sorter.add(element);
+        sorter.sorted(elements, it.key);
+    }
+}
+
 void CustomElementsRegistry::collectCandidates(
     const CustomElementDescriptor& desc,
     HeapVector<Member<Element>>* elements)
@@ -276,11 +310,19 @@ void CustomElementsRegistry::collectCandidates(
     UpgradeCandidateMap::iterator it = m_upgradeCandidates->find(desc.name());
     if (it == m_upgradeCandidates->end())
         return;
+
+    ElementsDocumentMap imports;
     CustomElementUpgradeSorter sorter;
     for (Element* element : *it.get()->value) {
         if (!element || !desc.matches(*element))
             continue;
-        sorter.add(element);
+
+        // Group elements by document if they are in import documents.
+        Document& document = element->document();
+        if (document == m_owner->document())
+            sorter.add(element);
+        else if (document.contextDocument() == m_owner->document())
+            addToImports(imports, element);
     }
 
     m_upgradeCandidates->remove(it);
@@ -289,6 +331,10 @@ void CustomElementsRegistry::collectCandidates(
     if (!document)
         return;
 
+    // If there were elements from import documents, put them first.
+    if (!imports.isEmpty())
+        collectFromImports(imports, elements);
+
     sorter.sorted(elements, document);
 }