Add exports needed for glue to build as a component.

webkit/extensions/v8/playback_extension.h

Index: webkit/extensions/v8/playback_extension.h
diff --git a/webkit/extensions/v8/playback_extension.h b/webkit/extensions/v8/playback_extension.h
index 3dc2be30796329b15a90e8fe924624a135c693e3..c425ea0aa710bea308b0762c164cdf7f3cd23800 100644
--- a/webkit/extensions/v8/playback_extension.h
+++ b/webkit/extensions/v8/playback_extension.h
@@ -6,6 +6,8 @@
 #define WEBKIT_EXTENSIONS_V8_PLAYBACK_EXTENSION_H_
 #pragma once
 
+#include "webkit/extensions/webkit_extensions_export.h"
+
 namespace v8 {
 class Extension;
 }
@@ -25,7 +27,7 @@ namespace extensions_v8 {
 // in exactly the same order in which they were recorded.
 class PlaybackExtension {
  public:
-  static v8::Extension* Get();
+  WEBKIT_EXTENSIONS_EXPORT static v8::Extension* Get();
 };
 
 }  // namespace extensions_v8