Add a flag to toggle how much downloads to retain.

This flag will be used to set how many days of downloads the storage
manager will retain while clearing data.

Bug: 30304998
Change-Id: I188f4ed3aaebde62d0bf4fe2838d171f0594895c
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 0b198cc..2cf7ca9 100755
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -6296,6 +6296,15 @@
                 "downloads_backup_charging_only";
 
         /**
+         * How many days of information for the automatic storage manager to retain on the device
+         * for downloads.
+         *
+         * @hide
+         */
+        public static final String AUTOMATIC_STORAGE_MANAGER_DOWNLOADS_DAYS_TO_RETAIN =
+                "automatic_storage_manager_downloads_days_to_retain";
+
+        /**
          * This are the settings to be backed up.
          *
          * NOTE: Settings are backed up and restored in the order they appear