call the parent implementation of onAttachedToWindow().

Bug: 7295909
Change-Id: I46d2d3b8cbd2e8f09e5820e82f97b64687fad2e1
diff --git a/src/com/android/dreams/basic/Colors.java b/src/com/android/dreams/basic/Colors.java
index c31ba8d..aaacfcd 100644
--- a/src/com/android/dreams/basic/Colors.java
+++ b/src/com/android/dreams/basic/Colors.java
@@ -65,6 +65,7 @@
 
     @Override
     public void onAttachedToWindow() {
+        super.onAttachedToWindow();
         setInteractive(false);
         setLowProfile(true);
         setFullscreen(true);