Fixing proguard related crash due to striping animation callbacks.

Change-Id: I7277ba232b1f2f0decf69ea0d2a2ece6948d5cb6
diff --git a/proguard.flags b/proguard.flags
index 010a1db..bedc5e7 100644
--- a/proguard.flags
+++ b/proguard.flags
@@ -32,6 +32,8 @@
 -keep class com.android.launcher2.Workspace {
   public float getBackgroundAlpha();
   public void setBackgroundAlpha(float);
+  public float getChildrenOutlineAlpha();
+  public void setChildrenOutlineAlpha(float);
 }
 
 -keep class com.android.launcher2.AllApps3D$Defines {