Fix NPE crash when using MockProperties

Override the setShow method in MockProperties as it is used for invalid
surface.

Bug: 295775097
Test: build
Change-Id: Id601fa3ce7408f236c77e41ccd60b7d8359c2e8c
diff --git a/quickstep/src/com/android/quickstep/util/SurfaceTransaction.java b/quickstep/src/com/android/quickstep/util/SurfaceTransaction.java
index 441f88d..5fd86c0 100644
--- a/quickstep/src/com/android/quickstep/util/SurfaceTransaction.java
+++ b/quickstep/src/com/android/quickstep/util/SurfaceTransaction.java
@@ -166,5 +166,10 @@
             this.shadowRadius = radius;
             return this;
         }
+
+        @Override
+        public SurfaceProperties setShow() {
+            return this;
+        }
     }
 }