[exp] ash: Ash in Mus.

ash/host/transformer_helper.h

Index: ash/host/transformer_helper.h
diff --git a/ash/host/transformer_helper.h b/ash/host/transformer_helper.h
index fdf315c9ed507a97bce8357b4711b91263374779..957b0c86c243e4a980ddd70c854ac49f7811dbdd 100644
--- a/ash/host/transformer_helper.h
+++ b/ash/host/transformer_helper.h
@@ -5,6 +5,7 @@
 #ifndef ASH_HOST_TRANSFORMER_HELPER_H_
 #define ASH_HOST_TRANSFORMER_HELPER_H_
 
+#include "ash/ash_export.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 
@@ -20,7 +21,7 @@ class RootWindowTransformer;
 
 // A helper class to handle ash specific feature that requires
 // transforming a root window (such as rotation, UI zooming).
-class TransformerHelper {
+class ASH_EXPORT TransformerHelper {
  public:
   explicit TransformerHelper(AshWindowTreeHost* ash_host);
   ~TransformerHelper();