Queue Custom Element attribute changes arising from style mutations.

third_party/WebKit/Source/core/css/PropertySetCSSStyleDeclaration.cpp

Index: third_party/WebKit/Source/core/css/PropertySetCSSStyleDeclaration.cpp
diff --git a/third_party/WebKit/Source/core/css/PropertySetCSSStyleDeclaration.cpp b/third_party/WebKit/Source/core/css/PropertySetCSSStyleDeclaration.cpp
index 3abfbc33959cc7cff27a2791e66d3d42d53c30b1..5cd3a039773c73553e14a2af40967536c6949e8a 100644
--- a/third_party/WebKit/Source/core/css/PropertySetCSSStyleDeclaration.cpp
+++ b/third_party/WebKit/Source/core/css/PropertySetCSSStyleDeclaration.cpp
@@ -31,6 +31,9 @@
 #include "core/dom/MutationObserverInterestGroup.h"
 #include "core/dom/MutationRecord.h"
 #include "core/dom/StyleEngine.h"
+#include "core/dom/custom/CustomElement.h"
+#include "core/dom/custom/CustomElementDefinition.h"
+#include "core/dom/custom/CustomElementLifecycleCallbacks.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "platform/RuntimeEnabledFeatures.h"
 
@@ -38,6 +41,11 @@ namespace blink {
 
 namespace {
 
+static bool isCustomElementWithAttributeChangedCallback(Element* element)
+{
+    return element->isUpgradedCustomElement() && element->customElementDefinition()->callbacks()->hasCallback(CustomElementLifecycleCallbacks::AttributeChangedCallback);
+}
+
 class StyleAttributeMutationScope {
     WTF_MAKE_NONCOPYABLE(StyleAttributeMutationScope);
     STACK_ALLOCATED();
@@ -57,18 +65,17 @@ public:
         if (!s_currentDecl->parentElement())
             return;
 
-        bool shouldReadOldValue = false;
-
         m_mutationRecipients = MutationObserverInterestGroup::createForAttributesMutation(*s_currentDecl->parentElement(), HTMLNames::styleAttr);
-        if (m_mutationRecipients && m_mutationRecipients->isOldValueRequested())
-            shouldReadOldValue = true;
 
-        AtomicString oldValue;
+        bool shouldReadOldValue =
+            (m_mutationRecipients && m_mutationRecipients->isOldValueRequested())
+            || isCustomElementWithAttributeChangedCallback(s_currentDecl->parentElement());
+
         if (shouldReadOldValue)
-            oldValue = s_currentDecl->parentElement()->getAttribute(HTMLNames::styleAttr);
+            m_oldValue = s_currentDecl->parentElement()->getAttribute(HTMLNames::styleAttr);
 
         if (m_mutationRecipients) {
-            AtomicString requestedOldValue = m_mutationRecipients->isOldValueRequested() ? oldValue : nullAtom;
+            AtomicString requestedOldValue = m_mutationRecipients->isOldValueRequested() ? m_oldValue : nullAtom;
             m_mutation = MutationRecord::createAttributes(s_currentDecl->parentElement(), HTMLNames::styleAttr, requestedOldValue);
         }
     }
@@ -79,9 +86,12 @@ public:
         if (s_scopeCount)
             return;
 
-        if (m_mutation && s_shouldDeliver)
+        if (s_shouldDeliver && m_mutation)
             m_mutationRecipients->enqueueMutationRecord(m_mutation);
 
+        if (s_shouldDeliver && isCustomElementWithAttributeChangedCallback(s_currentDecl->parentElement()))
+            CustomElement::attributeDidChange(s_currentDecl->parentElement(), HTMLNames::styleAttr.localName(), m_oldValue, s_currentDecl->parentElement()->getAttribute(HTMLNames::styleAttr));
+
         s_shouldDeliver = false;
 
         // We have to clear internal state before calling Inspector's code.
@@ -114,6 +124,7 @@ private:
 
     OwnPtrWillBeMember<MutationObserverInterestGroup> m_mutationRecipients;
     RefPtrWillBeMember<MutationRecord> m_mutation;
+    AtomicString m_oldValue;
 };
 
 unsigned StyleAttributeMutationScope::s_scopeCount = 0;