Oilpan: Remove most WillBe types from the code base

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

 // 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.
 
 #ifndef FetchManager_h
 #define FetchManager_h
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "core/dom/ContextLifecycleObserver.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class ExecutionContext;
 class FetchRequestData;
 class ScriptState;
 
 class FetchManager final : public GarbageCollectedFinalized<FetchManager>, public ContextLifecycleObserver {
-    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(FetchManager);
+    USING_GARBAGE_COLLECTED_MIXIN(FetchManager);
 public:
     static FetchManager* create(ExecutionContext*);
     explicit FetchManager(ExecutionContext*);
     ~FetchManager();
     ScriptPromise fetch(ScriptState*, FetchRequestData*);
     void contextDestroyed() override;
     bool isStopped() const { return m_isStopped; }
 
     DECLARE_TRACE();
 
 private:
     class Loader;
 
     // Removes loader from |m_loaders|.
     void onLoaderFinished(Loader*);
 
     HeapHashSet<Member<Loader>> m_loaders;
     bool m_isStopped;
 };
 
 } // namespace blink
 
 #endif // FetchManager_h