Fix an edge case where early disconnect() can omit delivering of observation. crbug/607324

third_party/WebKit/Source/core/timing/PerformanceObserver.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 PerformanceObserver_h
 #define PerformanceObserver_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
+#include "core/CoreExport.h"
 #include "core/timing/PerformanceEntry.h"
 #include "platform/heap/Handle.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class ExceptionState;
 class PerformanceBase;
 class PerformanceObserverCallback;
 class PerformanceObserver;
 class PerformanceObserverInit;
 
 using PerformanceEntryVector = HeapVector<Member<PerformanceEntry>>;
 
-class PerformanceObserver final : public GarbageCollected<PerformanceObserver>, public ScriptWrappable {
+class CORE_EXPORT PerformanceObserver final : public GarbageCollected<PerformanceObserver>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
     friend class PerformanceBase;
 public:
     static PerformanceObserver* create(PerformanceBase*, PerformanceObserverCallback*);
     static void resumeSuspendedObservers();
 
     void observe(const PerformanceObserverInit&, ExceptionState&);
     void disconnect();
     void enqueuePerformanceEntry(PerformanceEntry&);
     PerformanceEntryTypeMask filterOptions() const { return m_filterOptions; }
 
     DECLARE_TRACE();
 
 private:
     explicit PerformanceObserver(PerformanceBase*, PerformanceObserverCallback*);
     void deliver();
     bool shouldBeSuspended() const;
 
     Member<PerformanceObserverCallback> m_callback;
     WeakMember<PerformanceBase> m_performance;
     PerformanceEntryVector m_performanceEntries;
     PerformanceEntryTypeMask m_filterOptions;
     bool m_isRegistered;
 };
 
 } // namespace blink
 
 #endif // PerformanceObserver_h