[wrapper-tracing] Untangle non-trivial mixin ctors

third_party/WebKit/Source/modules/fetch/FetchManager.cpp

Index: third_party/WebKit/Source/modules/fetch/FetchManager.cpp
diff --git a/third_party/WebKit/Source/modules/fetch/FetchManager.cpp b/third_party/WebKit/Source/modules/fetch/FetchManager.cpp
index c62ef76229be9d2a765098793714c03f648b896c..e505e7f7be72e6b7cdef8b82936c11d2134416d0 100644
--- a/third_party/WebKit/Source/modules/fetch/FetchManager.cpp
+++ b/third_party/WebKit/Source/modules/fetch/FetchManager.cpp
@@ -410,14 +410,14 @@ void FetchManager::Loader::didReceiveResponse(
   FetchResponseData* responseData = nullptr;
   SRIBytesConsumer* sriConsumer = nullptr;
   if (m_request->integrity().isEmpty()) {
-    responseData = FetchResponseData::createWithBuffer(new BodyStreamBuffer(
+    responseData = FetchResponseData::createWithBuffer(BodyStreamBuffer::create(
         scriptState,
         new BytesConsumerForDataConsumerHandle(
             scriptState->getExecutionContext(), std::move(handle))));
   } else {
     sriConsumer = new SRIBytesConsumer();
     responseData = FetchResponseData::createWithBuffer(
-        new BodyStreamBuffer(scriptState, sriConsumer));
+        BodyStreamBuffer::create(scriptState, sriConsumer));
   }
   responseData->setStatus(response.httpStatusCode());
   responseData->setStatusMessage(response.httpStatusText());