fix a memory corruption where a SF Client could be used after it's been destroyed
diff --git a/libs/surfaceflinger/LayerDim.cpp b/libs/surfaceflinger/LayerDim.cpp
index b95e184..5cb883c 100644
--- a/libs/surfaceflinger/LayerDim.cpp
+++ b/libs/surfaceflinger/LayerDim.cpp
@@ -40,7 +40,7 @@
 // ---------------------------------------------------------------------------
 
 LayerDim::LayerDim(SurfaceFlinger* flinger, DisplayID display,
-        Client* client, int32_t i)
+        const sp<Client>& client, int32_t i)
     : LayerBaseClient(flinger, display, client, i)
 {
 }