Split the CSSParserContext class out of CSSParserMode into its own file.

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

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 33 matching lines @@
 #include "wtf/HashSet.h"
 #include "wtf/ListHashSet.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class ExceptionState;
 class LocalFrame;
 class PerformanceObserver;
 class PerformanceTiming;
+class ResourceResponse;
 class ResourceTimingInfo;
 class UserTiming;
 
 using PerformanceEntryVector = HeapVector<Member<PerformanceEntry>>;
 using PerformanceObservers = HeapListHashSet<Member<PerformanceObserver>>;
 
 class CORE_EXPORT PerformanceBase : public EventTargetWithInlineData {
   friend class PerformanceBaseTest;
 
  public:
@@ skipping 104 matching lines @@
   PerformanceEntryTypeMask m_observerFilterOptions;
   PerformanceObservers m_observers;
   PerformanceObservers m_activeObservers;
   PerformanceObservers m_suspendedObservers;
   Timer<PerformanceBase> m_deliverObservationsTimer;
 };
 
 }  // namespace blink
 
 #endif  // PerformanceBase_h