Add tracing to custom elements operations

third_party/WebKit/Source/bindings/core/v8/V8HTMLConstructor.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 "bindings/core/v8/V8HTMLConstructor.h"
 
 #include "bindings/core/v8/DOMWrapperWorld.h"
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ScriptCustomElementDefinition.h"
 #include "bindings/core/v8/V8Binding.h"
 #include "bindings/core/v8/V8BindingMacros.h"
 #include "bindings/core/v8/V8DOMWrapper.h"
 #include "bindings/core/v8/V8HTMLElement.h"
 #include "bindings/core/v8/V8PerContextData.h"
 #include "bindings/core/v8/V8ThrowException.h"
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/custom/CustomElementRegistry.h"
 #include "core/frame/LocalDOMWindow.h"
 #include "platform/RuntimeEnabledFeatures.h"
+#include "platform/tracing/TraceEvent.h"
 
 namespace blink {
 
 // https://html.spec.whatwg.org/multipage/dom.html#html-element-constructors
 void V8HTMLConstructor::htmlConstructor(
     const v8::FunctionCallbackInfo<v8::Value>& info,
     const WrapperTypeInfo& wrapperTypeInfo,
     const HTMLElementType elementInterfaceName) {
+  TRACE_EVENT0("blink", "HTMLConstructor");
   DCHECK(info.IsConstructCall());
 
   v8::Isolate* isolate = info.GetIsolate();
   ScriptState* scriptState = ScriptState::current(isolate);
   v8::Local<v8::Value> newTarget = info.NewTarget();
 
   if (!scriptState->contextIsValid()) {
     V8ThrowException::throwError(isolate, "The context has been destroyed");
     return;
   }
@@ skipping 103 matching lines @@
   // If the element had a wrapper, we now update and return that
   // instead.
   v8SetReturnValue(info, wrapper);
 
   // 11. Perform element.[[SetPrototypeOf]](prototype). Rethrow any exceptions.
   // Note: I don't think this prototype set *can* throw exceptions.
   wrapper->SetPrototype(scriptState->context(), prototype.As<v8::Object>())
       .ToChecked();
 }
 }  // namespace blink