Verify that FetchEvent::m_request holds same-thread reference.

third_party/WebKit/Source/modules/serviceworkers/FetchEvent.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 FetchEvent_h
 #define FetchEvent_h
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptPromiseProperty.h"
 #include "modules/EventModules.h"
@@ skipping 56 matching lines @@
  protected:
   FetchEvent(ScriptState*,
              const AtomicString& type,
              const FetchEventInit&,
              RespondWithObserver*,
              WaitUntilObserver*,
              bool navigationPreloadSent);
 
  private:
   Member<RespondWithObserver> m_observer;
-  Member<Request> m_request;
+  // TODO(sof): remove once crbug.com/655926 has been diagnosed.
+  SameThreadCheckedMember<Request> m_request;
   Member<PreloadResponseProperty> m_preloadResponseProperty;
   String m_clientId;
   bool m_isReload;
 };
 
 }  // namespace blink
 
 #endif  // FetchEvent_h