fix [3385504] Surface flinger hang when adding dim surface

Change-Id: I8e0cda414bcad5854d2ca5dde8370bfd8b2e5ea4
diff --git a/services/surfaceflinger/LayerBase.cpp b/services/surfaceflinger/LayerBase.cpp
index 464841b..8d83f0b 100644
--- a/services/surfaceflinger/LayerBase.cpp
+++ b/services/surfaceflinger/LayerBase.cpp
@@ -563,10 +563,15 @@
     if (s == 0) {
         s = createSurface();
         mClientSurface = s;
+        mClientSurfaceBinder = s->asBinder();
     }
     return s;
 }
 
+wp<IBinder> LayerBaseClient::getSurfaceBinder() const {
+    return mClientSurfaceBinder;
+}
+
 sp<LayerBaseClient::Surface> LayerBaseClient::createSurface() const
 {
     return new Surface(mFlinger, mIdentity,