Fix a race that could cause GL commands to be executed from the wrong thread.

Change-Id: Ia3d407f7bf2f5553f46cfdade70b7b0badb35beb
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 128f93d..278d64e 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -82,7 +82,6 @@
     virtual bool isSecure() const           { return mSecure; }
     virtual bool isProtected() const;
     virtual sp<Surface> createSurface() const;
-    virtual status_t ditch();
     virtual void onRemoved();
 
     // only for debugging
@@ -93,6 +92,7 @@
         return mFreezeLock; }
 
 protected:
+    virtual void destroy() const;
     virtual void dump(String8& result, char* scratch, size_t size) const;
 
 private: