Add exports needed for glue to build as a component.

webkit/extensions/v8/gc_extension.h

 // Copyright (c) 2011 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 WEBKIT_EXTENSIONS_V8_GC_EXTENSION_H_
 #define WEBKIT_EXTENSIONS_V8_GC_EXTENSION_H_
 #pragma once
 
+#include "webkit/extensions/webkit_extensions_export.h"
+
 namespace v8 {
 class Extension;
 }
 
 namespace extensions_v8 {
 
 // GCExtension is a v8 extension to expose a method into JS for triggering
 // garbage collection. This should only be used for debugging.
 class GCExtension {
  public:
-  static v8::Extension* Get();
+  WEBKIT_EXTENSIONS_EXPORT static v8::Extension* Get();
 };
 
 }  // namespace extensions_v8
 
 #endif  // WEBKIT_EXTENSIONS_V8_GC_EXTENSION_H_