cmsdk: add persisted key value for status bar tiles

The persisted one simply contains the user, the publishing package, and
the tile tag - items which can be persisted across reboots to restore
the tile's properties on boot properly.

Ticket: CYNGNOS-2530

Change-Id: If770557482e81ab0dd0d16c3ac8be0b2b51e653a
Signed-off-by: Roman Birg <roman@cyngn.com>

sdk/src/java/cyanogenmod/app/StatusBarPanelCustomTile.java

@@ -132,6 +132,11 @@ public class StatusBarPanelCustomTile implements Parcelable {
         return user.getIdentifier() + "|" + pkg + "|" + id + "|" + tag + "|" + uid;
     }
 
+    /** @hide */
+    public String persistableKey() {
+        return user.getIdentifier() + "|" + pkg + "|" + tag;
+    }
+
     public static final Creator<StatusBarPanelCustomTile> CREATOR
             = new Creator<StatusBarPanelCustomTile>()
     {