Add a use counter to customElements.define.

third_party/WebKit/Source/core/dom/custom/CustomElementRegistry.idl

Index: third_party/WebKit/Source/core/dom/custom/CustomElementRegistry.idl
diff --git a/third_party/WebKit/Source/core/dom/custom/CustomElementRegistry.idl b/third_party/WebKit/Source/core/dom/custom/CustomElementRegistry.idl
index 781451a703457a4055923ffe8f88536e6e3d327d..3741912f947669ad33f514b5c03742581d4cdebc 100644
--- a/third_party/WebKit/Source/core/dom/custom/CustomElementRegistry.idl
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElementRegistry.idl
@@ -5,7 +5,7 @@
 [
     RuntimeEnabled=CustomElementsV1,
 ] interface CustomElementRegistry {
-    [CallWith=ScriptState, CEReactions, CustomElementCallbacks, RaisesException] void define(DOMString name, Function constructor, optional ElementDefinitionOptions options);
+    [CallWith=ScriptState, CEReactions, CustomElementCallbacks, RaisesException, MeasureAs=CustomElementRegistryDefine] void define(DOMString name, Function constructor, optional ElementDefinitionOptions options);
     any get(DOMString name);
     [CallWith=ScriptState,RaisesException] Promise<void> whenDefined(DOMString name);
 };