Split the constructor of ThreadableLoader into two methods (ctor and start())

Source/modules/fetch/FetchManager.cpp

 // Copyright 2014 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 "config.h"
 #include "modules/fetch/FetchManager.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/ScriptState.h"
@@ skipping 363 matching lines @@
         threadableLoaderOptions.crossOriginRequestPolicy = DenyCrossOriginRequests;
         break;
     case WebURLRequest::FetchRequestModeNoCORS:
         threadableLoaderOptions.crossOriginRequestPolicy = AllowCrossOriginRequests;
         break;
     case WebURLRequest::FetchRequestModeCORS:
     case WebURLRequest::FetchRequestModeCORSWithForcedPreflight:
         threadableLoaderOptions.crossOriginRequestPolicy = UseAccessControl;
         break;
     }
-    m_loader = ThreadableLoader::create(*executionContext(), this, request, threadableLoaderOptions, resourceLoaderOptions);
-    if (!m_loader)
-        performNetworkError("Can't create ThreadableLoader");
+    m_loader = ThreadableLoader::create(*executionContext(), this, threadableLoaderOptions, resourceLoaderOptions);
+    m_loader->start(request);
 }
 
 void FetchManager::Loader::failed(const String& message)
 {
     if (m_failed || m_finished)
         return;
     m_failed = true;
     if (!message.isEmpty())
         executionContext()->addConsoleMessage(ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, message));
     if (m_resolver) {
@@ skipping 57 matching lines @@
 
 DEFINE_TRACE(FetchManager)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_executionContext);
     visitor->trace(m_loaders);
 #endif
 }
 
 } // namespace blink