blink: Cleanup class/struct forward declarations

third_party/WebKit/Source/core/timing/PerformanceLongTaskTiming.h

 // Copyright 2016 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 PerformanceLongTaskTiming_h
 #define PerformanceLongTaskTiming_h
 
 #include "core/timing/PerformanceEntry.h"
 #include "platform/heap/Handle.h"
 #include "wtf/Forward.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
-class DOMWindow;
-
 class PerformanceLongTaskTiming final : public PerformanceEntry {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
   static PerformanceLongTaskTiming* create(double startTime,
                                            double endTime,
                                            String name,
                                            String culpritFrameSrc,
                                            String culpritFrameId,
                                            String culpritFrameName) {
@@ skipping 18 matching lines @@
   ~PerformanceLongTaskTiming() override;
 
   String m_culpritFrameSrc;
   String m_culpritFrameId;
   String m_culpritFrameName;
 };
 
 }  // namespace blink
 
 #endif  // PerformanceLongTaskTiming_h