fix RefBase so it retains binary-compatibility with gingerbread

Bug: 4595257
Change-Id: I0d5e10f497e3f39868bff58f6ded510c38b44b12
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 72e290c..e3fc13d 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -45,7 +45,7 @@
 
 // ---------------------------------------------------------------------------
 
-class Layer : public LayerBaseClient
+class Layer : public LayerBaseClient, private RefBase::Destroyer
 {
 public:
             Layer(SurfaceFlinger* flinger, DisplayID display,
@@ -79,7 +79,7 @@
     inline const sp<FreezeLock>&  getFreezeLock() const { return mFreezeLock; }
 
 protected:
-    virtual void destroy() const;
+    virtual void destroy(RefBase const* base);
     virtual void onFirstRef();
     virtual void dump(String8& result, char* scratch, size_t size) const;