Setup infrastructure (multi-db support) for the new grid migration algorithm

We'll have a db for each grid option and a db for back up / restore.

TODO(pinyaoting): support back up / restore using the new infrastructure, particularly calls to GridBackupTable should use different DBs when the feature flag (NEW_GRID_MIGRATION_ALGORITHM) is on.

Bug: 144052802
Test: N/A

Change-Id: I644a3e70148bd78204a747a337446a3c038f616f
diff --git a/src/com/android/launcher3/LauncherFiles.java b/src/com/android/launcher3/LauncherFiles.java
index 9c4646b..25afb55 100644
--- a/src/com/android/launcher3/LauncherFiles.java
+++ b/src/com/android/launcher3/LauncherFiles.java
@@ -15,8 +15,13 @@
     private static final String XML = ".xml";
 
     public static final String LAUNCHER_DB = "launcher.db";
+    public static final String LAUNCHER_4_BY_4_DB = "launcher_4_by_4.db";
+    public static final String LAUNCHER_3_BY_3_DB = "launcher_3_by_3.db";
+    public static final String LAUNCHER_2_BY_2_DB = "launcher_2_by_2.db";
+    public static final String BACKUP_DB = "backup.db";
     public static final String SHARED_PREFERENCES_KEY = "com.android.launcher3.prefs";
-    public static final String MANAGED_USER_PREFERENCES_KEY = "com.android.launcher3.managedusers.prefs";
+    public static final String MANAGED_USER_PREFERENCES_KEY =
+            "com.android.launcher3.managedusers.prefs";
     // This preference file is not backed up to cloud.
     public static final String DEVICE_PREFERENCES_KEY = "com.android.launcher3.device.prefs";
 
@@ -25,6 +30,10 @@
 
     public static final List<String> ALL_FILES = Collections.unmodifiableList(Arrays.asList(
             LAUNCHER_DB,
+            LAUNCHER_4_BY_4_DB,
+            LAUNCHER_3_BY_3_DB,
+            LAUNCHER_2_BY_2_DB,
+            BACKUP_DB,
             SHARED_PREFERENCES_KEY + XML,
             WIDGET_PREVIEWS_DB,
             MANAGED_USER_PREFERENCES_KEY + XML,