Adding graphic for all apps empty search screen.

Change-Id: I976a327a5984790c458b0f36d33c0b1ac16ec59c
diff --git a/proguard.flags b/proguard.flags
index e6c4c51..5a3dfd1 100644
--- a/proguard.flags
+++ b/proguard.flags
@@ -2,6 +2,11 @@
   *;
 }
 
+-keep class com.android.launcher3.allapps.AllAppsBackgroundDrawable {
+  public void setAlpha(int);
+  public int getAlpha();
+}
+
 -keep class com.android.launcher3.BaseRecyclerViewFastScrollBar {
   public void setThumbWidth(int);
   public int getThumbWidth();