blink: Cleanup class/struct forward declarations

third_party/WebKit/Source/modules/background_sync/SyncManager.h

 // Copyright 2015 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 SyncManager_h
 #define SyncManager_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "platform/heap/Handle.h"
 #include "public/platform/modules/background_sync/background_sync.mojom-blink.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
-class ExecutionContext;
 class ScriptPromise;
 class ScriptPromiseResolver;
 class ScriptState;
 class ServiceWorkerRegistration;
 
 class SyncManager final : public GarbageCollectedFinalized<SyncManager>,
                           public ScriptWrappable {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
@@ skipping 25 matching lines @@
       mojom::blink::BackgroundSyncError,
       WTF::Vector<mojom::blink::SyncRegistrationPtr> registrations);
 
   Member<ServiceWorkerRegistration> m_registration;
   mojom::blink::BackgroundSyncServicePtr m_backgroundSyncService;
 };
 
 }  // namespace blink
 
 #endif  // SyncManager_h