Creating a custom drawable to customize shadow.

> Fixing DrapTargetBar set to visible (with alpha = 0) in the start
causing unnecessary draw

Bug: 37616877
Change-Id: Iaaff96099910f504f6e2f81c9376ddacde50ff6a
diff --git a/proguard.flags b/proguard.flags
index 6cbab08..2ad9cac 100644
--- a/proguard.flags
+++ b/proguard.flags
@@ -82,6 +82,10 @@
   *;
 }
 
+-keep class com.android.launcher3.graphics.ShadowDrawable {
+  public <init>(...);
+}
+
 # Proguard will strip methods required for talkback to properly scroll to
 # next row when focus is on the last item of last row when using a RecyclerView
 # Keep optimized and shrunk proguard to prevent issues like this when using