Removing GridMigrationTask-v1 since it has been disabled for a while

Also removing some data migration support

Bug: 194937047
Test: Presubmit
Change-Id: I392a5f6e49ec170f63056a7664de47229896f390
diff --git a/src/com/android/launcher3/LauncherProvider.java b/src/com/android/launcher3/LauncherProvider.java
index a8ed6bc..95a8d81 100644
--- a/src/com/android/launcher3/LauncherProvider.java
+++ b/src/com/android/launcher3/LauncherProvider.java
@@ -16,7 +16,6 @@
 
 package com.android.launcher3;
 
-import static com.android.launcher3.config.FeatureFlags.MULTI_DB_GRID_MIRATION_ALGO;
 import static com.android.launcher3.provider.LauncherDbUtils.copyTable;
 import static com.android.launcher3.provider.LauncherDbUtils.dropTable;
 import static com.android.launcher3.provider.LauncherDbUtils.tableExists;
@@ -433,32 +432,26 @@
                 return null;
             }
             case LauncherSettings.Settings.METHOD_UPDATE_CURRENT_OPEN_HELPER: {
-                if (MULTI_DB_GRID_MIRATION_ALGO.get()) {
-                    Bundle result = new Bundle();
-                    result.putBoolean(LauncherSettings.Settings.EXTRA_VALUE,
-                            prepForMigration(
-                                    InvariantDeviceProfile.INSTANCE.get(getContext()).dbFile,
-                                    Favorites.TMP_TABLE,
-                                    () -> mOpenHelper,
-                                    () -> DatabaseHelper.createDatabaseHelper(
-                                            getContext(), true /* forMigration */)));
-                    return result;
-                }
-                return null;
+                Bundle result = new Bundle();
+                result.putBoolean(LauncherSettings.Settings.EXTRA_VALUE,
+                        prepForMigration(
+                                InvariantDeviceProfile.INSTANCE.get(getContext()).dbFile,
+                                Favorites.TMP_TABLE,
+                                () -> mOpenHelper,
+                                () -> DatabaseHelper.createDatabaseHelper(
+                                        getContext(), true /* forMigration */)));
+                return result;
             }
             case LauncherSettings.Settings.METHOD_PREP_FOR_PREVIEW: {
-                if (MULTI_DB_GRID_MIRATION_ALGO.get()) {
-                    Bundle result = new Bundle();
-                    result.putBoolean(LauncherSettings.Settings.EXTRA_VALUE,
-                            prepForMigration(
-                                    arg /* dbFile */,
-                                    Favorites.PREVIEW_TABLE_NAME,
-                                    () -> DatabaseHelper.createDatabaseHelper(
-                                            getContext(), arg, true /* forMigration */),
-                                    () -> mOpenHelper));
-                    return result;
-                }
-                return null;
+                Bundle result = new Bundle();
+                result.putBoolean(LauncherSettings.Settings.EXTRA_VALUE,
+                        prepForMigration(
+                                arg /* dbFile */,
+                                Favorites.PREVIEW_TABLE_NAME,
+                                () -> DatabaseHelper.createDatabaseHelper(
+                                        getContext(), arg, true /* forMigration */),
+                                () -> mOpenHelper));
+                return result;
             }
             case LauncherSettings.Settings.METHOD_SWITCH_DATABASE: {
                 if (TextUtils.equals(arg, mOpenHelper.getDatabaseName())) return null;
@@ -654,8 +647,7 @@
         static DatabaseHelper createDatabaseHelper(Context context, String dbName,
                 boolean forMigration) {
             if (dbName == null) {
-                dbName = MULTI_DB_GRID_MIRATION_ALGO.get() ? InvariantDeviceProfile.INSTANCE.get(
-                        context).dbFile : LauncherFiles.LAUNCHER_DB;
+                dbName = InvariantDeviceProfile.INSTANCE.get(context).dbFile;
             }
             DatabaseHelper databaseHelper = new DatabaseHelper(context, dbName, forMigration);
             // Table creation sometimes fails silently, which leads to a crash loop.
@@ -666,10 +658,6 @@
                 // This operation is a no-op if the table already exists.
                 databaseHelper.addFavoritesTable(databaseHelper.getWritableDatabase(), true);
             }
-            if (!MULTI_DB_GRID_MIRATION_ALGO.get()) {
-                databaseHelper.mBackupTableExists = tableExists(
-                        databaseHelper.getReadableDatabase(), Favorites.BACKUP_TABLE_NAME);
-            }
             databaseHelper.mHotseatRestoreTableExists = tableExists(
                     databaseHelper.getReadableDatabase(), Favorites.HYBRID_HOTSEAT_BACKUP_TABLE);
 
@@ -851,11 +839,7 @@
                 case 25:
                     convertShortcutsToLauncherActivities(db);
                 case 26:
-                    // QSB was moved to the grid. Clear the first row on screen 0.
-                    if (FeatureFlags.QSB_ON_FIRST_SCREEN &&
-                            !LauncherDbUtils.prepareScreenZeroToHostQsb(mContext, db)) {
-                        break;
-                    }
+                    // QSB was moved to the grid. Ignore overlapping items
                 case 27: {
                     // Update the favorites table so that the screen ids are ordered based on
                     // workspace page rank.
diff --git a/src/com/android/launcher3/config/FeatureFlags.java b/src/com/android/launcher3/config/FeatureFlags.java
index 9b71918..33ee951 100644
--- a/src/com/android/launcher3/config/FeatureFlags.java
+++ b/src/com/android/launcher3/config/FeatureFlags.java
@@ -144,9 +144,6 @@
     public static final BooleanFlag ENABLE_DEEP_SHORTCUT_ICON_CACHE = getDebugFlag(
             "ENABLE_DEEP_SHORTCUT_ICON_CACHE", true, "R/W deep shortcut in IconCache");
 
-    public static final BooleanFlag MULTI_DB_GRID_MIRATION_ALGO = getDebugFlag(
-            "MULTI_DB_GRID_MIRATION_ALGO", true, "Use the multi-db grid migration algorithm");
-
     public static final BooleanFlag ENABLE_THEMED_ICONS = getDebugFlag(
             "ENABLE_THEMED_ICONS", true, "Enable themed icons on workspace");
 
diff --git a/src/com/android/launcher3/graphics/PreviewSurfaceRenderer.java b/src/com/android/launcher3/graphics/PreviewSurfaceRenderer.java
index d0464a4..c7448dc 100644
--- a/src/com/android/launcher3/graphics/PreviewSurfaceRenderer.java
+++ b/src/com/android/launcher3/graphics/PreviewSurfaceRenderer.java
@@ -16,7 +16,6 @@
 
 package com.android.launcher3.graphics;
 
-import static com.android.launcher3.config.FeatureFlags.MULTI_DB_GRID_MIRATION_ALGO;
 import static com.android.launcher3.util.Executors.MAIN_EXECUTOR;
 import static com.android.launcher3.util.Executors.MODEL_EXECUTOR;
 
@@ -47,7 +46,6 @@
 import com.android.launcher3.Workspace;
 import com.android.launcher3.graphics.LauncherPreviewRenderer.PreviewContext;
 import com.android.launcher3.model.BgDataModel;
-import com.android.launcher3.model.GridSizeMigrationTask;
 import com.android.launcher3.model.GridSizeMigrationTaskV2;
 import com.android.launcher3.model.LoaderTask;
 import com.android.launcher3.model.ModelDelegate;
@@ -198,16 +196,10 @@
 
     @WorkerThread
     private boolean doGridMigrationIfNecessary() {
-        boolean needsToMigrate =
-                MULTI_DB_GRID_MIRATION_ALGO.get()
-                        ? GridSizeMigrationTaskV2.needsToMigrate(mContext, mIdp)
-                        : GridSizeMigrationTask.needsToMigrate(mContext, mIdp);
-        if (!needsToMigrate) {
+        if (!GridSizeMigrationTaskV2.needsToMigrate(mContext, mIdp)) {
             return false;
         }
-        return MULTI_DB_GRID_MIRATION_ALGO.get()
-                ? GridSizeMigrationTaskV2.migrateGridIfNeeded(mContext, mIdp)
-                : GridSizeMigrationTask.migrateGridIfNeeded(mContext, mIdp);
+        return GridSizeMigrationTaskV2.migrateGridIfNeeded(mContext, mIdp);
     }
 
     @UiThread
diff --git a/src/com/android/launcher3/model/GridBackupTable.java b/src/com/android/launcher3/model/GridBackupTable.java
index acfc339..51cbf4b 100644
--- a/src/com/android/launcher3/model/GridBackupTable.java
+++ b/src/com/android/launcher3/model/GridBackupTable.java
@@ -23,14 +23,12 @@
 import android.content.Context;
 import android.database.Cursor;
 import android.database.sqlite.SQLiteDatabase;
-import android.graphics.Point;
 import android.os.Process;
 import android.util.Log;
 
 import androidx.annotation.IntDef;
 
 import com.android.launcher3.LauncherSettings.Favorites;
-import com.android.launcher3.LauncherSettings.Settings;
 import com.android.launcher3.pm.UserCache;
 
 /**
@@ -85,49 +83,6 @@
     }
 
     /**
-     * Create a backup from current workspace layout if one isn't created already (Note backup
-     * created this way is always sanitized). Otherwise restore from the backup instead.
-     */
-    public boolean backupOrRestoreAsNeeded() {
-        // Check if backup table exists
-        if (!tableExists(mDb, BACKUP_TABLE_NAME)) {
-            if (Settings.call(mContext.getContentResolver(), Settings.METHOD_WAS_EMPTY_DB_CREATED)
-                    .getBoolean(Settings.EXTRA_VALUE, false)) {
-                // No need to copy if empty DB was created.
-                return false;
-            }
-            doBackup(UserCache.INSTANCE.get(mContext).getSerialNumberForUser(
-                    Process.myUserHandle()), 0);
-            return false;
-        }
-        return restoreIfBackupExists(Favorites.TABLE_NAME);
-    }
-
-    public boolean restoreToPreviewIfBackupExists() {
-        if (!tableExists(mDb, BACKUP_TABLE_NAME)) {
-            return false;
-        }
-
-        return restoreIfBackupExists(Favorites.PREVIEW_TABLE_NAME);
-    }
-
-    private boolean restoreIfBackupExists(String toTableName) {
-        if (loadDBProperties() != STATE_SANITIZED) {
-            return false;
-        }
-        long userSerial = UserCache.INSTANCE.get(mContext).getSerialNumberForUser(
-                Process.myUserHandle());
-        copyTable(mDb, BACKUP_TABLE_NAME, toTableName, userSerial);
-        Log.d(TAG, "Backup table found");
-        return true;
-    }
-
-    public int getRestoreHotseatAndGridSize(Point outGridSize) {
-        outGridSize.set(mRestoredGridX, mRestoredGridY);
-        return mRestoredHotseatSize;
-    }
-
-    /**
      * Creates a new table and populates with copy of Favorites.TABLE_NAME
      */
     public void createCustomBackupTable(String tableName) {
diff --git a/src/com/android/launcher3/model/GridSizeMigrationTask.java b/src/com/android/launcher3/model/GridSizeMigrationTask.java
deleted file mode 100644
index 7b3e509..0000000
--- a/src/com/android/launcher3/model/GridSizeMigrationTask.java
+++ /dev/null
@@ -1,1098 +0,0 @@
-package com.android.launcher3.model;
-
-import static com.android.launcher3.InvariantDeviceProfile.KEY_MIGRATION_SRC_HOTSEAT_COUNT;
-import static com.android.launcher3.InvariantDeviceProfile.KEY_MIGRATION_SRC_WORKSPACE_SIZE;
-import static com.android.launcher3.LauncherSettings.Settings.EXTRA_VALUE;
-import static com.android.launcher3.Utilities.getPointString;
-import static com.android.launcher3.Utilities.parsePoint;
-import static com.android.launcher3.provider.LauncherDbUtils.copyTable;
-
-import android.content.ComponentName;
-import android.content.ContentValues;
-import android.content.Context;
-import android.content.Intent;
-import android.content.SharedPreferences;
-import android.content.pm.PackageInfo;
-import android.content.pm.PackageManager;
-import android.database.Cursor;
-import android.database.sqlite.SQLiteDatabase;
-import android.graphics.Point;
-import android.os.SystemClock;
-import android.util.Log;
-import android.util.SparseArray;
-
-import androidx.annotation.VisibleForTesting;
-
-import com.android.launcher3.InvariantDeviceProfile;
-import com.android.launcher3.LauncherAppState;
-import com.android.launcher3.LauncherSettings;
-import com.android.launcher3.LauncherSettings.Favorites;
-import com.android.launcher3.LauncherSettings.Settings;
-import com.android.launcher3.Utilities;
-import com.android.launcher3.Workspace;
-import com.android.launcher3.config.FeatureFlags;
-import com.android.launcher3.graphics.LauncherPreviewRenderer;
-import com.android.launcher3.model.data.ItemInfo;
-import com.android.launcher3.pm.InstallSessionHelper;
-import com.android.launcher3.provider.LauncherDbUtils;
-import com.android.launcher3.provider.LauncherDbUtils.SQLiteTransaction;
-import com.android.launcher3.util.GridOccupancy;
-import com.android.launcher3.util.IntArray;
-import com.android.launcher3.util.IntSparseArrayMap;
-import com.android.launcher3.widget.LauncherAppWidgetProviderInfo;
-import com.android.launcher3.widget.WidgetManagerHelper;
-
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashSet;
-
-/**
- * This class takes care of shrinking the workspace (by maximum of one row and one column), as a
- * result of restoring from a larger device or device density change.
- */
-public class GridSizeMigrationTask {
-
-    private static final String TAG = "GridSizeMigrationTask";
-    private static final boolean DEBUG = false;
-
-    // These are carefully selected weights for various item types (Math.random?), to allow for
-    // the least absurd migration experience.
-    private static final float WT_SHORTCUT = 1;
-    private static final float WT_APPLICATION = 0.8f;
-    private static final float WT_WIDGET_MIN = 2;
-    private static final float WT_WIDGET_FACTOR = 0.6f;
-    private static final float WT_FOLDER_FACTOR = 0.5f;
-
-    protected final SQLiteDatabase mDb;
-    protected final Context mContext;
-
-    protected final IntArray mEntryToRemove = new IntArray();
-    protected final ArrayList<DbEntry> mCarryOver = new ArrayList<>();
-
-    private final SparseArray<ContentValues> mUpdateOperations = new SparseArray<>();
-    private final HashSet<String> mValidPackages;
-    private final String mTableName;
-
-    private final int mSrcX, mSrcY;
-    private final int mTrgX, mTrgY;
-    private final boolean mShouldRemoveX, mShouldRemoveY;
-
-    private final int mSrcHotseatSize;
-    private final int mDestHotseatSize;
-
-    protected GridSizeMigrationTask(Context context, SQLiteDatabase db,
-            HashSet<String> validPackages, boolean usePreviewTable, Point sourceSize,
-            Point targetSize) {
-        mContext = context;
-        mDb = db;
-        mValidPackages = validPackages;
-        mTableName = usePreviewTable ? Favorites.PREVIEW_TABLE_NAME : Favorites.TABLE_NAME;
-
-        mSrcX = sourceSize.x;
-        mSrcY = sourceSize.y;
-
-        mTrgX = targetSize.x;
-        mTrgY = targetSize.y;
-
-        mShouldRemoveX = mTrgX < mSrcX;
-        mShouldRemoveY = mTrgY < mSrcY;
-
-        // Non-used variables
-        mSrcHotseatSize = mDestHotseatSize = -1;
-    }
-
-    protected GridSizeMigrationTask(Context context, SQLiteDatabase db,
-            HashSet<String> validPackages, boolean usePreviewTable, int srcHotseatSize,
-            int destHotseatSize) {
-        mContext = context;
-        mDb = db;
-        mValidPackages = validPackages;
-        mTableName = usePreviewTable ? Favorites.PREVIEW_TABLE_NAME : Favorites.TABLE_NAME;
-
-        mSrcHotseatSize = srcHotseatSize;
-
-        mDestHotseatSize = destHotseatSize;
-
-        // Non-used variables
-        mSrcX = mSrcY = mTrgX = mTrgY = -1;
-        mShouldRemoveX = mShouldRemoveY = false;
-    }
-
-    /**
-     * Applied all the pending DB operations
-     *
-     * @return true if any DB operation was commited.
-     */
-    private boolean applyOperations() throws Exception {
-        // Update items
-        int updateCount = mUpdateOperations.size();
-        for (int i = 0; i < updateCount; i++) {
-            mDb.update(mTableName, mUpdateOperations.valueAt(i),
-                    "_id=" + mUpdateOperations.keyAt(i), null);
-        }
-
-        if (!mEntryToRemove.isEmpty()) {
-            if (DEBUG) {
-                Log.d(TAG, "Removing items: " + mEntryToRemove.toConcatString());
-            }
-            mDb.delete(mTableName, Utilities.createDbSelectionQuery(Favorites._ID, mEntryToRemove),
-                    null);
-        }
-
-        return updateCount > 0 || !mEntryToRemove.isEmpty();
-    }
-
-    /**
-     * To migrate hotseat, we load all the entries in order (LTR or RTL) and arrange them
-     * in the order in the new hotseat while keeping an empty space for all-apps. If the number of
-     * entries is more than what can fit in the new hotseat, we drop the entries with least weight.
-     * For weight calculation {@see #WT_SHORTCUT}, {@see #WT_APPLICATION}
-     * & {@see #WT_FOLDER_FACTOR}.
-     *
-     * @return true if any DB change was made
-     */
-    protected boolean migrateHotseat() throws Exception {
-        ArrayList<DbEntry> items = loadHotseatEntries();
-        while (items.size() > mDestHotseatSize) {
-            // Pick the center item by default.
-            DbEntry toRemove = items.get(items.size() / 2);
-
-            // Find the item with least weight.
-            for (DbEntry entry : items) {
-                if (entry.weight < toRemove.weight) {
-                    toRemove = entry;
-                }
-            }
-
-            mEntryToRemove.add(toRemove.id);
-            items.remove(toRemove);
-        }
-
-        // Update screen IDS
-        int newScreenId = 0;
-        for (DbEntry entry : items) {
-            if (entry.screenId != newScreenId) {
-                entry.screenId = newScreenId;
-
-                // These values does not affect the item position, but we should set them
-                // to something other than -1.
-                entry.cellX = newScreenId;
-                entry.cellY = 0;
-
-                update(entry);
-            }
-
-            newScreenId++;
-        }
-
-        return applyOperations();
-    }
-
-    @VisibleForTesting
-    static IntArray getWorkspaceScreenIds(SQLiteDatabase db, String tableName) {
-        return LauncherDbUtils.queryIntArray(db, tableName, Favorites.SCREEN,
-                Favorites.CONTAINER + " = " + Favorites.CONTAINER_DESKTOP,
-                Favorites.SCREEN, Favorites.SCREEN);
-    }
-
-    /**
-     * @return true if any DB change was made
-     */
-    protected boolean migrateWorkspace() throws Exception {
-        IntArray allScreens = getWorkspaceScreenIds(mDb, mTableName);
-        if (allScreens.isEmpty()) {
-            throw new Exception("Unable to get workspace screens");
-        }
-
-        for (int i = 0; i < allScreens.size(); i++) {
-            int screenId = allScreens.get(i);
-            if (DEBUG) {
-                Log.d(TAG, "Migrating " + screenId);
-            }
-            migrateScreen(screenId);
-        }
-
-        if (!mCarryOver.isEmpty()) {
-            IntSparseArrayMap<DbEntry> itemMap = new IntSparseArrayMap<>();
-            for (DbEntry e : mCarryOver) {
-                itemMap.put(e.id, e);
-            }
-
-            do {
-                // Some items are still remaining. Try adding a few new screens.
-
-                // At every iteration, make sure that at least one item is removed from
-                // {@link #mCarryOver}, to prevent an infinite loop. If no item could be removed,
-                // break the loop and abort migration by throwing an exception.
-                OptimalPlacementSolution placement = new OptimalPlacementSolution(
-                        new GridOccupancy(mTrgX, mTrgY), deepCopy(mCarryOver), 0, true);
-                placement.find();
-                if (placement.finalPlacedItems.size() > 0) {
-                    int newScreenId = LauncherSettings.Settings.call(
-                            mContext.getContentResolver(),
-                            LauncherSettings.Settings.METHOD_NEW_SCREEN_ID)
-                            .getInt(EXTRA_VALUE);
-                    for (DbEntry item : placement.finalPlacedItems) {
-                        if (!mCarryOver.remove(itemMap.get(item.id))) {
-                            throw new Exception("Unable to find matching items");
-                        }
-                        item.screenId = newScreenId;
-                        update(item);
-                    }
-                } else {
-                    throw new Exception("None of the items can be placed on an empty screen");
-                }
-
-            } while (!mCarryOver.isEmpty());
-        }
-        return applyOperations();
-    }
-
-    /**
-     * Migrate a particular screen id.
-     * Strategy:
-     *  1) For all possible combinations of row and column, pick the one which causes the least
-     *    data loss: {@link #tryRemove(int, int, int, ArrayList, float[])}
-     *  2) Maintain a list of all lost items before this screen, and add any new item lost from
-     *    this screen to that list as well.
-     *  3) If all those items from the above list can be placed on this screen, place them
-     *    (otherwise they are placed on a new screen).
-     */
-    protected void migrateScreen(int screenId) {
-        // If we are migrating the first screen, do not touch the first row.
-        int startY = (FeatureFlags.QSB_ON_FIRST_SCREEN && screenId == Workspace.FIRST_SCREEN_ID)
-                ? 1 : 0;
-
-        ArrayList<DbEntry> items = loadWorkspaceEntries(screenId);
-
-        int removedCol = Integer.MAX_VALUE;
-        int removedRow = Integer.MAX_VALUE;
-
-        // removeWt represents the cost function for loss of items during migration, and moveWt
-        // represents the cost function for repositioning the items. moveWt is only considered if
-        // removeWt is same for two different configurations.
-        // Start with Float.MAX_VALUE (assuming full data) and pick the configuration with least
-        // cost.
-        float removeWt = Float.MAX_VALUE;
-        float moveWt = Float.MAX_VALUE;
-        float[] outLoss = new float[2];
-        ArrayList<DbEntry> finalItems = null;
-
-        // Try removing all possible combinations
-        for (int x = 0; x < mSrcX; x++) {
-            // Try removing the rows first from bottom. This keeps the workspace
-            // nicely aligned with hotseat.
-            for (int y = mSrcY - 1; y >= startY; y--) {
-                // Use a deep copy when trying out a particular combination as it can change
-                // the underlying object.
-                ArrayList<DbEntry> itemsOnScreen = tryRemove(x, y, startY, deepCopy(items),
-                        outLoss);
-
-                if ((outLoss[0] < removeWt) || ((outLoss[0] == removeWt) && (outLoss[1]
-                        < moveWt))) {
-                    removeWt = outLoss[0];
-                    moveWt = outLoss[1];
-                    removedCol = mShouldRemoveX ? x : removedCol;
-                    removedRow = mShouldRemoveY ? y : removedRow;
-                    finalItems = itemsOnScreen;
-                }
-
-                // No need to loop over all rows, if a row removal is not needed.
-                if (!mShouldRemoveY) {
-                    break;
-                }
-            }
-
-            if (!mShouldRemoveX) {
-                break;
-            }
-        }
-
-        if (DEBUG) {
-            Log.d(TAG, String.format("Removing row %d, column %d on screen %d",
-                    removedRow, removedCol, screenId));
-        }
-
-        IntSparseArrayMap<DbEntry> itemMap = new IntSparseArrayMap<>();
-        for (DbEntry e : deepCopy(items)) {
-            itemMap.put(e.id, e);
-        }
-
-        for (DbEntry item : finalItems) {
-            DbEntry org = itemMap.get(item.id);
-            itemMap.remove(item.id);
-
-            // Check if update is required
-            if (!item.columnsSame(org)) {
-                update(item);
-            }
-        }
-
-        // The remaining items in {@link #itemMap} are those which didn't get placed.
-        for (DbEntry item : itemMap) {
-            mCarryOver.add(item);
-        }
-
-        if (!mCarryOver.isEmpty() && removeWt == 0) {
-            // No new items were removed in this step. Try placing all the items on this screen.
-            GridOccupancy occupied = new GridOccupancy(mTrgX, mTrgY);
-            occupied.markCells(0, 0, mTrgX, startY, true);
-            for (DbEntry item : finalItems) {
-                occupied.markCells(item, true);
-            }
-
-            OptimalPlacementSolution placement = new OptimalPlacementSolution(occupied,
-                    deepCopy(mCarryOver), startY, true);
-            placement.find();
-            if (placement.lowestWeightLoss == 0) {
-                // All items got placed
-
-                for (DbEntry item : placement.finalPlacedItems) {
-                    item.screenId = screenId;
-                    update(item);
-                }
-
-                mCarryOver.clear();
-            }
-        }
-    }
-
-    /**
-     * Updates an item in the DB.
-     */
-    protected void update(DbEntry item) {
-        ContentValues values = new ContentValues();
-        item.addToContentValues(values);
-        mUpdateOperations.put(item.id, values);
-    }
-
-    /**
-     * Tries the remove the provided row and column.
-     *
-     * @param items   all the items on the screen under operation
-     * @param outLoss array of size 2. The first entry is filled with weight loss, and the second
-     *                with the overall item movement.
-     */
-    private ArrayList<DbEntry> tryRemove(int col, int row, int startY,
-            ArrayList<DbEntry> items, float[] outLoss) {
-        GridOccupancy occupied = new GridOccupancy(mTrgX, mTrgY);
-        occupied.markCells(0, 0, mTrgX, startY, true);
-
-        col = mShouldRemoveX ? col : Integer.MAX_VALUE;
-        row = mShouldRemoveY ? row : Integer.MAX_VALUE;
-
-        ArrayList<DbEntry> finalItems = new ArrayList<>();
-        ArrayList<DbEntry> removedItems = new ArrayList<>();
-
-        for (DbEntry item : items) {
-            if ((item.cellX <= col && (item.spanX + item.cellX) > col)
-                    || (item.cellY <= row && (item.spanY + item.cellY) > row)) {
-                removedItems.add(item);
-                if (item.cellX >= col) item.cellX--;
-                if (item.cellY >= row) item.cellY--;
-            } else {
-                if (item.cellX > col) item.cellX--;
-                if (item.cellY > row) item.cellY--;
-                finalItems.add(item);
-                occupied.markCells(item, true);
-            }
-        }
-
-        OptimalPlacementSolution placement =
-                new OptimalPlacementSolution(occupied, removedItems, startY);
-        placement.find();
-        finalItems.addAll(placement.finalPlacedItems);
-        outLoss[0] = placement.lowestWeightLoss;
-        outLoss[1] = placement.lowestMoveCost;
-        return finalItems;
-    }
-
-    private class OptimalPlacementSolution {
-        private final ArrayList<DbEntry> itemsToPlace;
-        private final GridOccupancy occupied;
-
-        // If set to true, item movement are not considered in move cost, leading to a more
-        // linear placement.
-        private final boolean ignoreMove;
-
-        // The first row in the grid from where the placement should start.
-        private final int startY;
-
-        float lowestWeightLoss = Float.MAX_VALUE;
-        float lowestMoveCost = Float.MAX_VALUE;
-        ArrayList<DbEntry> finalPlacedItems;
-
-        public OptimalPlacementSolution(
-                GridOccupancy occupied, ArrayList<DbEntry> itemsToPlace, int startY) {
-            this(occupied, itemsToPlace, startY, false);
-        }
-
-        public OptimalPlacementSolution(GridOccupancy occupied, ArrayList<DbEntry> itemsToPlace,
-                int startY, boolean ignoreMove) {
-            this.occupied = occupied;
-            this.itemsToPlace = itemsToPlace;
-            this.ignoreMove = ignoreMove;
-            this.startY = startY;
-
-            // Sort the items such that larger widgets appear first followed by 1x1 items
-            Collections.sort(this.itemsToPlace);
-        }
-
-        public void find() {
-            find(0, 0, 0, new ArrayList<DbEntry>());
-        }
-
-        /**
-         * Recursively finds a placement for the provided items.
-         *
-         * @param index       the position in {@link #itemsToPlace} to start looking at.
-         * @param weightLoss  total weight loss upto this point
-         * @param moveCost    total move cost upto this point
-         * @param itemsPlaced all the items already placed upto this point
-         */
-        public void find(int index, float weightLoss, float moveCost,
-                ArrayList<DbEntry> itemsPlaced) {
-            if ((weightLoss >= lowestWeightLoss) ||
-                    ((weightLoss == lowestWeightLoss) && (moveCost >= lowestMoveCost))) {
-                // Abort, as we already have a better solution.
-                return;
-
-            } else if (index >= itemsToPlace.size()) {
-                // End loop.
-                lowestWeightLoss = weightLoss;
-                lowestMoveCost = moveCost;
-
-                // Keep a deep copy of current configuration as it can change during recursion.
-                finalPlacedItems = deepCopy(itemsPlaced);
-                return;
-            }
-
-            DbEntry me = itemsToPlace.get(index);
-            int myX = me.cellX;
-            int myY = me.cellY;
-
-            // List of items to pass over if this item was placed.
-            ArrayList<DbEntry> itemsIncludingMe = new ArrayList<>(itemsPlaced.size() + 1);
-            itemsIncludingMe.addAll(itemsPlaced);
-            itemsIncludingMe.add(me);
-
-            if (me.spanX > 1 || me.spanY > 1) {
-                // If the current item is a widget (and it greater than 1x1), try to place it at
-                // all possible positions. This is because a widget placed at one position can
-                // affect the placement of a different widget.
-                int myW = me.spanX;
-                int myH = me.spanY;
-
-                for (int y = startY; y < mTrgY; y++) {
-                    for (int x = 0; x < mTrgX; x++) {
-                        float newMoveCost = moveCost;
-                        if (x != myX) {
-                            me.cellX = x;
-                            newMoveCost++;
-                        }
-                        if (y != myY) {
-                            me.cellY = y;
-                            newMoveCost++;
-                        }
-                        if (ignoreMove) {
-                            newMoveCost = moveCost;
-                        }
-
-                        if (occupied.isRegionVacant(x, y, myW, myH)) {
-                            // place at this position and continue search.
-                            occupied.markCells(me, true);
-                            find(index + 1, weightLoss, newMoveCost, itemsIncludingMe);
-                            occupied.markCells(me, false);
-                        }
-
-                        // Try resizing horizontally
-                        if (myW > me.minSpanX && occupied.isRegionVacant(x, y, myW - 1, myH)) {
-                            me.spanX--;
-                            occupied.markCells(me, true);
-                            // 1 extra move cost
-                            find(index + 1, weightLoss, newMoveCost + 1, itemsIncludingMe);
-                            occupied.markCells(me, false);
-                            me.spanX++;
-                        }
-
-                        // Try resizing vertically
-                        if (myH > me.minSpanY && occupied.isRegionVacant(x, y, myW, myH - 1)) {
-                            me.spanY--;
-                            occupied.markCells(me, true);
-                            // 1 extra move cost
-                            find(index + 1, weightLoss, newMoveCost + 1, itemsIncludingMe);
-                            occupied.markCells(me, false);
-                            me.spanY++;
-                        }
-
-                        // Try resizing horizontally & vertically
-                        if (myH > me.minSpanY && myW > me.minSpanX &&
-                                occupied.isRegionVacant(x, y, myW - 1, myH - 1)) {
-                            me.spanX--;
-                            me.spanY--;
-                            occupied.markCells(me, true);
-                            // 2 extra move cost
-                            find(index + 1, weightLoss, newMoveCost + 2, itemsIncludingMe);
-                            occupied.markCells(me, false);
-                            me.spanX++;
-                            me.spanY++;
-                        }
-                        me.cellX = myX;
-                        me.cellY = myY;
-                    }
-                }
-
-                // Finally also try a solution when this item is not included. Trying it in the end
-                // causes it to get skipped in most cases due to higher weight loss, and prevents
-                // unnecessary deep copies of various configurations.
-                find(index + 1, weightLoss + me.weight, moveCost, itemsPlaced);
-            } else {
-                // Since this is a 1x1 item and all the following items are also 1x1, just place
-                // it at 'the most appropriate position' and hope for the best.
-                // The most appropriate position: one with lease straight line distance
-                int newDistance = Integer.MAX_VALUE;
-                int newX = Integer.MAX_VALUE, newY = Integer.MAX_VALUE;
-
-                for (int y = startY; y < mTrgY; y++) {
-                    for (int x = 0; x < mTrgX; x++) {
-                        if (!occupied.cells[x][y]) {
-                            int dist = ignoreMove ? 0 :
-                                    ((me.cellX - x) * (me.cellX - x) + (me.cellY - y) * (me.cellY
-                                            - y));
-                            if (dist < newDistance) {
-                                newX = x;
-                                newY = y;
-                                newDistance = dist;
-                            }
-                        }
-                    }
-                }
-
-                if (newX < mTrgX && newY < mTrgY) {
-                    float newMoveCost = moveCost;
-                    if (newX != myX) {
-                        me.cellX = newX;
-                        newMoveCost++;
-                    }
-                    if (newY != myY) {
-                        me.cellY = newY;
-                        newMoveCost++;
-                    }
-                    if (ignoreMove) {
-                        newMoveCost = moveCost;
-                    }
-                    occupied.markCells(me, true);
-                    find(index + 1, weightLoss, newMoveCost, itemsIncludingMe);
-                    occupied.markCells(me, false);
-                    me.cellX = myX;
-                    me.cellY = myY;
-
-                    // Try to find a solution without this item, only if
-                    //  1) there was at least one space, i.e., we were able to place this item
-                    //  2) if the next item has the same weight (all items are already sorted), as
-                    //     if it has lower weight, that solution will automatically get discarded.
-                    //  3) ignoreMove false otherwise, move cost is ignored and the weight will
-                    //      anyway be same.
-                    if (index + 1 < itemsToPlace.size()
-                            && itemsToPlace.get(index + 1).weight >= me.weight && !ignoreMove) {
-                        find(index + 1, weightLoss + me.weight, moveCost, itemsPlaced);
-                    }
-                } else {
-                    // No more space. Jump to the end.
-                    for (int i = index + 1; i < itemsToPlace.size(); i++) {
-                        weightLoss += itemsToPlace.get(i).weight;
-                    }
-                    find(itemsToPlace.size(), weightLoss + me.weight, moveCost, itemsPlaced);
-                }
-            }
-        }
-    }
-
-    private ArrayList<DbEntry> loadHotseatEntries() {
-        Cursor c = queryWorkspace(
-                new String[]{
-                        Favorites._ID,                  // 0
-                        Favorites.ITEM_TYPE,            // 1
-                        Favorites.INTENT,               // 2
-                        Favorites.SCREEN},              // 3
-                Favorites.CONTAINER + " = " + Favorites.CONTAINER_HOTSEAT);
-
-        final int indexId = c.getColumnIndexOrThrow(Favorites._ID);
-        final int indexItemType = c.getColumnIndexOrThrow(Favorites.ITEM_TYPE);
-        final int indexIntent = c.getColumnIndexOrThrow(Favorites.INTENT);
-        final int indexScreen = c.getColumnIndexOrThrow(Favorites.SCREEN);
-
-        ArrayList<DbEntry> entries = new ArrayList<>();
-        while (c.moveToNext()) {
-            DbEntry entry = new DbEntry();
-            entry.id = c.getInt(indexId);
-            entry.itemType = c.getInt(indexItemType);
-            entry.screenId = c.getInt(indexScreen);
-
-            if (entry.screenId >= mSrcHotseatSize) {
-                mEntryToRemove.add(entry.id);
-                continue;
-            }
-
-            try {
-                // calculate weight
-                switch (entry.itemType) {
-                    case Favorites.ITEM_TYPE_SHORTCUT:
-                    case Favorites.ITEM_TYPE_DEEP_SHORTCUT:
-                    case Favorites.ITEM_TYPE_APPLICATION: {
-                        verifyIntent(c.getString(indexIntent));
-                        entry.weight = entry.itemType == Favorites.ITEM_TYPE_APPLICATION ?
-                                WT_APPLICATION : WT_SHORTCUT;
-                        break;
-                    }
-                    case Favorites.ITEM_TYPE_FOLDER: {
-                        int total = getFolderItemsCount(entry.id);
-                        if (total == 0) {
-                            throw new Exception("Folder is empty");
-                        }
-                        entry.weight = WT_FOLDER_FACTOR * total;
-                        break;
-                    }
-                    default:
-                        throw new Exception("Invalid item type");
-                }
-            } catch (Exception e) {
-                if (DEBUG) {
-                    Log.d(TAG, "Removing item " + entry.id, e);
-                }
-                mEntryToRemove.add(entry.id);
-                continue;
-            }
-            entries.add(entry);
-        }
-        c.close();
-        return entries;
-    }
-
-
-    /**
-     * Loads entries for a particular screen id.
-     */
-    protected ArrayList<DbEntry> loadWorkspaceEntries(int screen) {
-        Cursor c = queryWorkspace(
-                new String[]{
-                        Favorites._ID,                  // 0
-                        Favorites.ITEM_TYPE,            // 1
-                        Favorites.CELLX,                // 2
-                        Favorites.CELLY,                // 3
-                        Favorites.SPANX,                // 4
-                        Favorites.SPANY,                // 5
-                        Favorites.INTENT,               // 6
-                        Favorites.APPWIDGET_PROVIDER,   // 7
-                        Favorites.APPWIDGET_ID},        // 8
-                Favorites.CONTAINER + " = " + Favorites.CONTAINER_DESKTOP
-                        + " AND " + Favorites.SCREEN + " = " + screen);
-
-        final int indexId = c.getColumnIndexOrThrow(Favorites._ID);
-        final int indexItemType = c.getColumnIndexOrThrow(Favorites.ITEM_TYPE);
-        final int indexCellX = c.getColumnIndexOrThrow(Favorites.CELLX);
-        final int indexCellY = c.getColumnIndexOrThrow(Favorites.CELLY);
-        final int indexSpanX = c.getColumnIndexOrThrow(Favorites.SPANX);
-        final int indexSpanY = c.getColumnIndexOrThrow(Favorites.SPANY);
-        final int indexIntent = c.getColumnIndexOrThrow(Favorites.INTENT);
-        final int indexAppWidgetProvider = c.getColumnIndexOrThrow(Favorites.APPWIDGET_PROVIDER);
-        final int indexAppWidgetId = c.getColumnIndexOrThrow(Favorites.APPWIDGET_ID);
-
-        ArrayList<DbEntry> entries = new ArrayList<>();
-        WidgetManagerHelper widgetManagerHelper = new WidgetManagerHelper(mContext);
-        while (c.moveToNext()) {
-            DbEntry entry = new DbEntry();
-            entry.id = c.getInt(indexId);
-            entry.itemType = c.getInt(indexItemType);
-            entry.cellX = c.getInt(indexCellX);
-            entry.cellY = c.getInt(indexCellY);
-            entry.spanX = c.getInt(indexSpanX);
-            entry.spanY = c.getInt(indexSpanY);
-            entry.screenId = screen;
-
-            try {
-                // calculate weight
-                switch (entry.itemType) {
-                    case Favorites.ITEM_TYPE_SHORTCUT:
-                    case Favorites.ITEM_TYPE_DEEP_SHORTCUT:
-                    case Favorites.ITEM_TYPE_APPLICATION: {
-                        verifyIntent(c.getString(indexIntent));
-                        entry.weight = entry.itemType == Favorites.ITEM_TYPE_APPLICATION ?
-                                WT_APPLICATION : WT_SHORTCUT;
-                        break;
-                    }
-                    case Favorites.ITEM_TYPE_APPWIDGET: {
-                        String provider = c.getString(indexAppWidgetProvider);
-                        ComponentName cn = ComponentName.unflattenFromString(provider);
-                        verifyPackage(cn.getPackageName());
-                        entry.weight = Math.max(WT_WIDGET_MIN, WT_WIDGET_FACTOR
-                                * entry.spanX * entry.spanY);
-
-                        int widgetId = c.getInt(indexAppWidgetId);
-                        LauncherAppWidgetProviderInfo pInfo =
-                                widgetManagerHelper.getLauncherAppWidgetInfo(widgetId);
-                        Point spans = null;
-                        if (pInfo != null) {
-                            spans = pInfo.getMinSpans();
-                        }
-                        if (spans != null) {
-                            entry.minSpanX = spans.x > 0 ? spans.x : entry.spanX;
-                            entry.minSpanY = spans.y > 0 ? spans.y : entry.spanY;
-                        } else {
-                            // Assume that the widget be resized down to 2x2
-                            entry.minSpanX = entry.minSpanY = 2;
-                        }
-
-                        if (entry.minSpanX > mTrgX || entry.minSpanY > mTrgY) {
-                            throw new Exception("Widget can't be resized down to fit the grid");
-                        }
-                        break;
-                    }
-                    case Favorites.ITEM_TYPE_FOLDER: {
-                        int total = getFolderItemsCount(entry.id);
-                        if (total == 0) {
-                            throw new Exception("Folder is empty");
-                        }
-                        entry.weight = WT_FOLDER_FACTOR * total;
-                        break;
-                    }
-                    default:
-                        throw new Exception("Invalid item type");
-                }
-            } catch (Exception e) {
-                if (DEBUG) {
-                    Log.d(TAG, "Removing item " + entry.id, e);
-                }
-                mEntryToRemove.add(entry.id);
-                continue;
-            }
-            entries.add(entry);
-        }
-        c.close();
-        return entries;
-    }
-
-    /**
-     * @return the number of valid items in the folder.
-     */
-    private int getFolderItemsCount(int folderId) {
-        Cursor c = queryWorkspace(
-                new String[]{Favorites._ID, Favorites.INTENT},
-                Favorites.CONTAINER + " = " + folderId);
-
-        int total = 0;
-        while (c.moveToNext()) {
-            try {
-                verifyIntent(c.getString(1));
-                total++;
-            } catch (Exception e) {
-                mEntryToRemove.add(c.getInt(0));
-            }
-        }
-        c.close();
-        return total;
-    }
-
-    protected Cursor queryWorkspace(String[] columns, String where) {
-        return mDb.query(mTableName, columns, where, null, null, null, null);
-    }
-
-    /**
-     * Verifies if the intent should be restored.
-     */
-    private void verifyIntent(String intentStr) throws Exception {
-        Intent intent = Intent.parseUri(intentStr, 0);
-        if (intent.getComponent() != null) {
-            verifyPackage(intent.getComponent().getPackageName());
-        } else if (intent.getPackage() != null) {
-            // Only verify package if the component was null.
-            verifyPackage(intent.getPackage());
-        }
-    }
-
-    /**
-     * Verifies if the package should be restored
-     */
-    private void verifyPackage(String packageName) throws Exception {
-        if (!mValidPackages.contains(packageName)) {
-            throw new Exception("Package not available");
-        }
-    }
-
-    protected static class DbEntry extends ItemInfo implements Comparable<DbEntry> {
-
-        public float weight;
-
-        public DbEntry() {
-        }
-
-        public DbEntry copy() {
-            DbEntry entry = new DbEntry();
-            entry.copyFrom(this);
-            entry.weight = weight;
-            entry.minSpanX = minSpanX;
-            entry.minSpanY = minSpanY;
-            return entry;
-        }
-
-        /**
-         * Comparator such that larger widgets come first,  followed by all 1x1 items
-         * based on their weights.
-         */
-        @Override
-        public int compareTo(DbEntry another) {
-            if (itemType == Favorites.ITEM_TYPE_APPWIDGET) {
-                if (another.itemType == Favorites.ITEM_TYPE_APPWIDGET) {
-                    return another.spanY * another.spanX - spanX * spanY;
-                } else {
-                    return -1;
-                }
-            } else if (another.itemType == Favorites.ITEM_TYPE_APPWIDGET) {
-                return 1;
-            } else {
-                // Place higher weight before lower weight.
-                return Float.compare(another.weight, weight);
-            }
-        }
-
-        public boolean columnsSame(DbEntry org) {
-            return org.cellX == cellX && org.cellY == cellY && org.spanX == spanX &&
-                    org.spanY == spanY && org.screenId == screenId;
-        }
-
-        public void addToContentValues(ContentValues values) {
-            values.put(Favorites.SCREEN, screenId);
-            values.put(Favorites.CELLX, cellX);
-            values.put(Favorites.CELLY, cellY);
-            values.put(Favorites.SPANX, spanX);
-            values.put(Favorites.SPANY, spanY);
-        }
-    }
-
-    private static ArrayList<DbEntry> deepCopy(ArrayList<DbEntry> src) {
-        ArrayList<DbEntry> dup = new ArrayList<>(src.size());
-        for (DbEntry e : src) {
-            dup.add(e.copy());
-        }
-        return dup;
-    }
-
-    public static void markForMigration(
-            Context context, int gridX, int gridY, int hotseatSize) {
-        Utilities.getPrefs(context).edit()
-                .putString(KEY_MIGRATION_SRC_WORKSPACE_SIZE, getPointString(gridX, gridY))
-                .putInt(KEY_MIGRATION_SRC_HOTSEAT_COUNT, hotseatSize)
-                .apply();
-    }
-
-    /**
-     * Check given a new IDP, if migration is necessary.
-     */
-    public static boolean needsToMigrate(Context context, InvariantDeviceProfile idp) {
-        SharedPreferences prefs = Utilities.getPrefs(context);
-        String gridSizeString = getPointString(idp.numColumns, idp.numRows);
-
-        return !gridSizeString.equals(prefs.getString(KEY_MIGRATION_SRC_WORKSPACE_SIZE, ""))
-                || idp.numDatabaseHotseatIcons != prefs.getInt(KEY_MIGRATION_SRC_HOTSEAT_COUNT, -1);
-    }
-
-    /** See {@link #migrateGridIfNeeded(Context, InvariantDeviceProfile)} */
-    public static boolean migrateGridIfNeeded(Context context) {
-        if (context instanceof LauncherPreviewRenderer.PreviewContext) {
-            return true;
-        }
-        return migrateGridIfNeeded(context, null);
-    }
-
-    /**
-     * Run the migration algorithm if needed. For preview, we provide the intended idp because it
-     * has not been changed. If idp is null, we read it from the context, for actual grid migration.
-     *
-     * @return false if the migration failed.
-     */
-    public static boolean migrateGridIfNeeded(Context context, InvariantDeviceProfile idp) {
-        boolean migrateForPreview = idp != null;
-        if (!migrateForPreview) {
-            idp = LauncherAppState.getIDP(context);
-        }
-
-        if (!needsToMigrate(context, idp)) {
-            return true;
-        }
-
-        SharedPreferences prefs = Utilities.getPrefs(context);
-        String gridSizeString = getPointString(idp.numColumns, idp.numRows);
-        long migrationStartTime = SystemClock.elapsedRealtime();
-        try (SQLiteTransaction transaction = (SQLiteTransaction) Settings.call(
-                context.getContentResolver(), Settings.METHOD_NEW_TRANSACTION)
-                .getBinder(Settings.EXTRA_VALUE)) {
-
-            int srcHotseatCount = prefs.getInt(KEY_MIGRATION_SRC_HOTSEAT_COUNT,
-                    idp.numDatabaseHotseatIcons);
-            Point sourceSize = parsePoint(prefs.getString(
-                    KEY_MIGRATION_SRC_WORKSPACE_SIZE, gridSizeString));
-
-            boolean dbChanged = false;
-            if (migrateForPreview) {
-                copyTable(transaction.getDb(), Favorites.TABLE_NAME, transaction.getDb(),
-                        Favorites.PREVIEW_TABLE_NAME, context);
-            }
-
-            GridBackupTable backupTable = new GridBackupTable(context, transaction.getDb(),
-                    srcHotseatCount, sourceSize.x, sourceSize.y);
-            if (migrateForPreview ? backupTable.restoreToPreviewIfBackupExists()
-                    : backupTable.backupOrRestoreAsNeeded()) {
-                dbChanged = true;
-                srcHotseatCount = backupTable.getRestoreHotseatAndGridSize(sourceSize);
-            }
-
-            HashSet<String> validPackages = getValidPackages(context);
-            // Hotseat.
-            if (srcHotseatCount != idp.numDatabaseHotseatIcons
-                    && new GridSizeMigrationTask(context, transaction.getDb(), validPackages,
-                            migrateForPreview, srcHotseatCount,
-                            idp.numDatabaseHotseatIcons).migrateHotseat()) {
-                dbChanged = true;
-            }
-
-            // Grid size
-            Point targetSize = new Point(idp.numColumns, idp.numRows);
-            if (new MultiStepMigrationTask(validPackages, context, transaction.getDb(),
-                    migrateForPreview).migrate(sourceSize, targetSize)) {
-                dbChanged = true;
-            }
-
-            if (dbChanged) {
-                // Make sure we haven't removed everything.
-                final Cursor c = context.getContentResolver().query(
-                        migrateForPreview ? Favorites.PREVIEW_CONTENT_URI : Favorites.CONTENT_URI,
-                        null, null, null, null);
-                boolean hasData = c.moveToNext();
-                c.close();
-                if (!hasData) {
-                    throw new Exception("Removed every thing during grid resize");
-                }
-            }
-
-            transaction.commit();
-            if (!migrateForPreview) {
-                Settings.call(context.getContentResolver(), Settings.METHOD_REFRESH_BACKUP_TABLE);
-            }
-            return true;
-        } catch (Exception e) {
-            Log.e(TAG, "Error during preview grid migration", e);
-
-            return false;
-        } finally {
-            Log.v(TAG, "Preview workspace migration completed in "
-                    + (SystemClock.elapsedRealtime() - migrationStartTime));
-
-            if (!migrateForPreview) {
-                // Save current configuration, so that the migration does not run again.
-                prefs.edit()
-                        .putString(KEY_MIGRATION_SRC_WORKSPACE_SIZE, gridSizeString)
-                        .putInt(KEY_MIGRATION_SRC_HOTSEAT_COUNT, idp.numDatabaseHotseatIcons)
-                        .apply();
-            }
-        }
-    }
-
-    protected static HashSet<String> getValidPackages(Context context) {
-        // Initialize list of valid packages. This contain all the packages which are already on
-        // the device and packages which are being installed. Any item which doesn't belong to
-        // this set is removed.
-        // Since the loader removes such items anyway, removing these items here doesn't cause
-        // any extra data loss and gives us more free space on the grid for better migration.
-        HashSet<String> validPackages = new HashSet<>();
-        for (PackageInfo info : context.getPackageManager()
-                .getInstalledPackages(PackageManager.GET_UNINSTALLED_PACKAGES)) {
-            validPackages.add(info.packageName);
-        }
-        InstallSessionHelper.INSTANCE.get(context)
-                .getActiveSessions().keySet()
-                .forEach(packageUserKey -> validPackages.add(packageUserKey.mPackageName));
-        return validPackages;
-    }
-
-    /**
-     * Removes any broken item from the hotseat.
-     *
-     * @return a map with occupied hotseat position set to non-null value.
-     */
-    public static IntSparseArrayMap<Object> removeBrokenHotseatItems(Context context)
-            throws Exception {
-        try (SQLiteTransaction transaction = (SQLiteTransaction) Settings.call(
-                context.getContentResolver(), Settings.METHOD_NEW_TRANSACTION)
-                .getBinder(Settings.EXTRA_VALUE)) {
-            GridSizeMigrationTask task = new GridSizeMigrationTask(
-                    context, transaction.getDb(), getValidPackages(context),
-                    false /* usePreviewTable */, Integer.MAX_VALUE, Integer.MAX_VALUE);
-
-            // Load all the valid entries
-            ArrayList<DbEntry> items = task.loadHotseatEntries();
-            // Delete any entry marked for deletion by above load.
-            task.applyOperations();
-            IntSparseArrayMap<Object> positions = new IntSparseArrayMap<>();
-            for (DbEntry item : items) {
-                positions.put(item.screenId, item);
-            }
-            transaction.commit();
-            return positions;
-        }
-    }
-
-    /**
-     * Task to run grid migration in multiple steps when the size difference is more than 1.
-     */
-    protected static class MultiStepMigrationTask {
-        private final HashSet<String> mValidPackages;
-        private final Context mContext;
-        private final SQLiteDatabase mDb;
-        private final boolean mUsePreviewTable;
-
-        public MultiStepMigrationTask(HashSet<String> validPackages, Context context,
-                SQLiteDatabase db, boolean usePreviewTable) {
-            mValidPackages = validPackages;
-            mContext = context;
-            mDb = db;
-            mUsePreviewTable = usePreviewTable;
-        }
-
-        public boolean migrate(Point sourceSize, Point targetSize) throws Exception {
-            boolean dbChanged = false;
-            if (!targetSize.equals(sourceSize)) {
-                if (sourceSize.x < targetSize.x) {
-                    // Source is smaller that target, just expand the grid without actual migration.
-                    sourceSize.x = targetSize.x;
-                }
-                if (sourceSize.y < targetSize.y) {
-                    // Source is smaller that target, just expand the grid without actual migration.
-                    sourceSize.y = targetSize.y;
-                }
-
-                // Migrate the workspace grid, such that the points differ by max 1 in x and y
-                // each on every step.
-                while (!targetSize.equals(sourceSize)) {
-                    // Get the next size, such that the points differ by max 1 in x and y each
-                    Point nextSize = new Point(sourceSize);
-                    if (targetSize.x < nextSize.x) {
-                        nextSize.x--;
-                    }
-                    if (targetSize.y < nextSize.y) {
-                        nextSize.y--;
-                    }
-                    if (runStepTask(sourceSize, nextSize)) {
-                        dbChanged = true;
-                    }
-                    sourceSize.set(nextSize.x, nextSize.y);
-                }
-            }
-            return dbChanged;
-        }
-
-        protected boolean runStepTask(Point sourceSize, Point nextSize) throws Exception {
-            return new GridSizeMigrationTask(mContext, mDb, mValidPackages, mUsePreviewTable,
-                    sourceSize, nextSize).migrateWorkspace();
-        }
-    }
-}
diff --git a/src/com/android/launcher3/model/LoaderTask.java b/src/com/android/launcher3/model/LoaderTask.java
index 43f9be5..1378a1a 100644
--- a/src/com/android/launcher3/model/LoaderTask.java
+++ b/src/com/android/launcher3/model/LoaderTask.java
@@ -17,7 +17,6 @@
 package com.android.launcher3.model;
 
 import static com.android.launcher3.WorkspaceLayoutManager.LEFT_PANEL_ID;
-import static com.android.launcher3.config.FeatureFlags.MULTI_DB_GRID_MIRATION_ALGO;
 import static com.android.launcher3.model.BgDataModel.Callbacks.FLAG_HAS_SHORTCUT_PERMISSION;
 import static com.android.launcher3.model.BgDataModel.Callbacks.FLAG_QUIET_MODE_CHANGE_PERMISSION;
 import static com.android.launcher3.model.BgDataModel.Callbacks.FLAG_QUIET_MODE_ENABLED;
@@ -80,7 +79,6 @@
 import com.android.launcher3.pm.InstallSessionHelper;
 import com.android.launcher3.pm.PackageInstallInfo;
 import com.android.launcher3.pm.UserCache;
-import com.android.launcher3.provider.ImportDataTask;
 import com.android.launcher3.qsb.QsbContainerView;
 import com.android.launcher3.shortcuts.ShortcutKey;
 import com.android.launcher3.shortcuts.ShortcutRequest;
@@ -334,16 +332,7 @@
         final WidgetManagerHelper widgetHelper = new WidgetManagerHelper(context);
 
         boolean clearDb = false;
-        try {
-            ImportDataTask.performImportIfPossible(context);
-        } catch (Exception e) {
-            // Migration failed. Clear workspace.
-            clearDb = true;
-        }
-
-        if (!clearDb && (MULTI_DB_GRID_MIRATION_ALGO.get()
-                ? !GridSizeMigrationTaskV2.migrateGridIfNeeded(context)
-                : !GridSizeMigrationTask.migrateGridIfNeeded(context))) {
+        if (!GridSizeMigrationTaskV2.migrateGridIfNeeded(context)) {
             // Migration failed. Clear workspace.
             clearDb = true;
         }
diff --git a/src/com/android/launcher3/provider/ImportDataTask.java b/src/com/android/launcher3/provider/ImportDataTask.java
deleted file mode 100644
index c9af2fe..0000000
--- a/src/com/android/launcher3/provider/ImportDataTask.java
+++ /dev/null
@@ -1,438 +0,0 @@
-/*
- * Copyright (C) 2016 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.android.launcher3.provider;
-
-import static com.android.launcher3.Utilities.getDevicePrefs;
-
-import android.content.ContentProviderOperation;
-import android.content.ContentValues;
-import android.content.Context;
-import android.content.Intent;
-import android.content.SharedPreferences;
-import android.content.pm.ApplicationInfo;
-import android.content.pm.PackageManager;
-import android.content.pm.ProviderInfo;
-import android.database.Cursor;
-import android.database.sqlite.SQLiteDatabase;
-import android.net.Uri;
-import android.os.Process;
-import android.text.TextUtils;
-import android.util.ArrayMap;
-import android.util.SparseBooleanArray;
-
-import com.android.launcher3.AutoInstallsLayout.LayoutParserCallback;
-import com.android.launcher3.DefaultLayoutParser;
-import com.android.launcher3.LauncherAppState;
-import com.android.launcher3.LauncherProvider;
-import com.android.launcher3.LauncherSettings;
-import com.android.launcher3.LauncherSettings.Favorites;
-import com.android.launcher3.LauncherSettings.Settings;
-import com.android.launcher3.Workspace;
-import com.android.launcher3.config.FeatureFlags;
-import com.android.launcher3.logging.FileLog;
-import com.android.launcher3.model.GridSizeMigrationTask;
-import com.android.launcher3.model.data.LauncherAppWidgetInfo;
-import com.android.launcher3.pm.UserCache;
-import com.android.launcher3.util.IntArray;
-import com.android.launcher3.util.IntSparseArrayMap;
-import com.android.launcher3.util.PackageManagerHelper;
-
-import java.net.URISyntaxException;
-import java.util.ArrayList;
-import java.util.HashSet;
-
-/**
- * Utility class to import data from another Launcher which is based on Launcher3 schema.
- */
-public class ImportDataTask {
-
-    public static final String KEY_DATA_IMPORT_SRC_PKG = "data_import_src_pkg";
-    public static final String KEY_DATA_IMPORT_SRC_AUTHORITY = "data_import_src_authority";
-
-    private static final String TAG = "ImportDataTask";
-    private static final int MIN_ITEM_COUNT_FOR_SUCCESSFUL_MIGRATION = 6;
-    // Insert items progressively to avoid OOM exception when loading icons.
-    private static final int BATCH_INSERT_SIZE = 15;
-
-    private final Context mContext;
-
-    private final Uri mOtherFavoritesUri;
-
-    private int mHotseatSize;
-    private int mMaxGridSizeX;
-    private int mMaxGridSizeY;
-
-    private ImportDataTask(Context context, String sourceAuthority) {
-        mContext = context;
-        mOtherFavoritesUri = Uri.parse("content://" + sourceAuthority + "/" + Favorites.TABLE_NAME);
-    }
-
-    public boolean importWorkspace() throws Exception {
-        FileLog.d(TAG, "Importing DB from " + mOtherFavoritesUri);
-
-        mHotseatSize = mMaxGridSizeX = mMaxGridSizeY = 0;
-        importWorkspaceItems();
-        GridSizeMigrationTask.markForMigration(mContext, mMaxGridSizeX, mMaxGridSizeY, mHotseatSize);
-
-        // Create empty DB flag.
-        LauncherSettings.Settings.call(mContext.getContentResolver(),
-                LauncherSettings.Settings.METHOD_CLEAR_EMPTY_DB_FLAG);
-        return true;
-    }
-
-    /**
-     * 1) Imports all the workspace entries from the source provider.
-     * 2) For home screen entries, maps the screen id based on {@param screenIdMap}
-     * 3) In the end fills any holes in hotseat with items from default hotseat layout.
-     */
-    private void importWorkspaceItems() throws Exception {
-        String profileId = Long.toString(UserCache.INSTANCE.get(mContext)
-                .getSerialNumberForUser(Process.myUserHandle()));
-
-        boolean createEmptyRowOnFirstScreen;
-        if (FeatureFlags.QSB_ON_FIRST_SCREEN) {
-            try (Cursor c = mContext.getContentResolver().query(mOtherFavoritesUri, null,
-                    // get items on the first row of the first screen (min screen id)
-                    "profileId = ? AND container = -100 AND cellY = 0 AND screen = " +
-                    "(SELECT MIN(screen) FROM favorites WHERE container = -100)",
-                    new String[]{profileId},
-                    null)) {
-                // First row of first screen is not empty
-                createEmptyRowOnFirstScreen = c.moveToNext();
-            }
-        } else {
-            createEmptyRowOnFirstScreen = false;
-        }
-
-        ArrayList<ContentProviderOperation> insertOperations = new ArrayList<>(BATCH_INSERT_SIZE);
-
-        // Set of package names present in hotseat
-        final HashSet<String> hotseatTargetApps = new HashSet<>();
-        int maxId = 0;
-
-        // Number of imported items on workspace and hotseat
-        int totalItemsOnWorkspace = 0;
-
-        try (Cursor c = mContext.getContentResolver()
-                .query(mOtherFavoritesUri, null,
-                        // Only migrate the primary user
-                        Favorites.PROFILE_ID + " = ?", new String[]{profileId},
-                        // Get the items sorted by container, so that the folders are loaded
-                        // before the corresponding items.
-                        Favorites.CONTAINER + " , " + Favorites.SCREEN)) {
-
-            // various columns we expect to exist.
-            final int idIndex = c.getColumnIndexOrThrow(Favorites._ID);
-            final int intentIndex = c.getColumnIndexOrThrow(Favorites.INTENT);
-            final int titleIndex = c.getColumnIndexOrThrow(Favorites.TITLE);
-            final int containerIndex = c.getColumnIndexOrThrow(Favorites.CONTAINER);
-            final int itemTypeIndex = c.getColumnIndexOrThrow(Favorites.ITEM_TYPE);
-            final int widgetProviderIndex = c.getColumnIndexOrThrow(Favorites.APPWIDGET_PROVIDER);
-            final int screenIndex = c.getColumnIndexOrThrow(Favorites.SCREEN);
-            final int cellXIndex = c.getColumnIndexOrThrow(Favorites.CELLX);
-            final int cellYIndex = c.getColumnIndexOrThrow(Favorites.CELLY);
-            final int spanXIndex = c.getColumnIndexOrThrow(Favorites.SPANX);
-            final int spanYIndex = c.getColumnIndexOrThrow(Favorites.SPANY);
-            final int rankIndex = c.getColumnIndexOrThrow(Favorites.RANK);
-            final int iconIndex = c.getColumnIndexOrThrow(Favorites.ICON);
-            final int iconPackageIndex = c.getColumnIndexOrThrow(Favorites.ICON_PACKAGE);
-            final int iconResourceIndex = c.getColumnIndexOrThrow(Favorites.ICON_RESOURCE);
-
-            SparseBooleanArray mValidFolders = new SparseBooleanArray();
-            ContentValues values = new ContentValues();
-
-            Integer firstScreenId = null;
-            while (c.moveToNext()) {
-                values.clear();
-                int id = c.getInt(idIndex);
-                maxId = Math.max(maxId, id);
-                int type = c.getInt(itemTypeIndex);
-                int container = c.getInt(containerIndex);
-
-                int screen = c.getInt(screenIndex);
-
-                int cellX = c.getInt(cellXIndex);
-                int cellY = c.getInt(cellYIndex);
-                int spanX = c.getInt(spanXIndex);
-                int spanY = c.getInt(spanYIndex);
-
-                switch (container) {
-                    case Favorites.CONTAINER_DESKTOP: {
-                        if (screen < Workspace.FIRST_SCREEN_ID) {
-                            FileLog.d(TAG, String.format(
-                                    "Skipping item %d, type %d not on a valid screen %d",
-                                    id, type, screen));
-                            continue;
-                        }
-                        if (firstScreenId == null) {
-                            firstScreenId = screen;
-                        }
-                        // Reset the screen to 0-index value
-                        if (createEmptyRowOnFirstScreen && firstScreenId.equals(screen)) {
-                            // Shift items by 1.
-                            cellY++;
-                            // Change the screen id to first screen
-                            screen = Workspace.FIRST_SCREEN_ID;
-                        }
-
-                        mMaxGridSizeX = Math.max(mMaxGridSizeX, cellX + spanX);
-                        mMaxGridSizeY = Math.max(mMaxGridSizeY, cellY + spanY);
-                        break;
-                    }
-                    case Favorites.CONTAINER_HOTSEAT: {
-                        mHotseatSize = Math.max(mHotseatSize, screen + 1);
-                        break;
-                    }
-                    default:
-                        if (!mValidFolders.get(container)) {
-                            FileLog.d(TAG, String.format("Skipping item %d, type %d not in a valid folder %d", id, type, container));
-                            continue;
-                        }
-                }
-
-                Intent intent = null;
-                switch (type) {
-                    case Favorites.ITEM_TYPE_FOLDER: {
-                        mValidFolders.put(id, true);
-                        // Use a empty intent to indicate a folder.
-                        intent = new Intent();
-                        break;
-                    }
-                    case Favorites.ITEM_TYPE_APPWIDGET: {
-                        values.put(Favorites.RESTORED,
-                                LauncherAppWidgetInfo.FLAG_ID_NOT_VALID |
-                                        LauncherAppWidgetInfo.FLAG_PROVIDER_NOT_READY |
-                                        LauncherAppWidgetInfo.FLAG_UI_NOT_READY);
-                        values.put(Favorites.APPWIDGET_PROVIDER, c.getString(widgetProviderIndex));
-                        break;
-                    }
-                    case Favorites.ITEM_TYPE_SHORTCUT:
-                    case Favorites.ITEM_TYPE_APPLICATION: {
-                        intent = Intent.parseUri(c.getString(intentIndex), 0);
-                        if (PackageManagerHelper.isLauncherAppTarget(intent)) {
-                            type = Favorites.ITEM_TYPE_APPLICATION;
-                        } else {
-                            values.put(Favorites.ICON_PACKAGE, c.getString(iconPackageIndex));
-                            values.put(Favorites.ICON_RESOURCE, c.getString(iconResourceIndex));
-                        }
-                        values.put(Favorites.ICON,  c.getBlob(iconIndex));
-                        values.put(Favorites.INTENT, intent.toUri(0));
-                        values.put(Favorites.RANK, c.getInt(rankIndex));
-
-                        values.put(Favorites.RESTORED, 1);
-                        break;
-                    }
-                    default:
-                        FileLog.d(TAG, String.format("Skipping item %d, not a valid type %d", id, type));
-                        continue;
-                }
-
-                if (container == Favorites.CONTAINER_HOTSEAT) {
-                    if (intent == null) {
-                        FileLog.d(TAG, String.format("Skipping item %d, null intent on hotseat", id));
-                        continue;
-                    }
-                    if (intent.getComponent() != null) {
-                        intent.setPackage(intent.getComponent().getPackageName());
-                    }
-                    hotseatTargetApps.add(getPackage(intent));
-                }
-
-                values.put(Favorites._ID, id);
-                values.put(Favorites.ITEM_TYPE, type);
-                values.put(Favorites.CONTAINER, container);
-                values.put(Favorites.SCREEN, screen);
-                values.put(Favorites.CELLX, cellX);
-                values.put(Favorites.CELLY, cellY);
-                values.put(Favorites.SPANX, spanX);
-                values.put(Favorites.SPANY, spanY);
-                values.put(Favorites.TITLE, c.getString(titleIndex));
-                insertOperations.add(ContentProviderOperation
-                        .newInsert(Favorites.CONTENT_URI).withValues(values).build());
-                if (container < 0) {
-                    totalItemsOnWorkspace++;
-                }
-
-                if (insertOperations.size() >= BATCH_INSERT_SIZE) {
-                    mContext.getContentResolver().applyBatch(LauncherProvider.AUTHORITY,
-                            insertOperations);
-                    insertOperations.clear();
-                }
-            }
-        }
-        FileLog.d(TAG, totalItemsOnWorkspace + " items imported from external source");
-        if (totalItemsOnWorkspace < MIN_ITEM_COUNT_FOR_SUCCESSFUL_MIGRATION) {
-            throw new Exception("Insufficient data");
-        }
-        if (!insertOperations.isEmpty()) {
-            mContext.getContentResolver().applyBatch(LauncherProvider.AUTHORITY,
-                    insertOperations);
-            insertOperations.clear();
-        }
-
-        IntSparseArrayMap<Object> hotseatItems = GridSizeMigrationTask
-                .removeBrokenHotseatItems(mContext);
-        int myHotseatCount = LauncherAppState.getIDP(mContext).numDatabaseHotseatIcons;
-        if (hotseatItems.size() < myHotseatCount) {
-            // Insufficient hotseat items. Add a few more.
-            HotseatParserCallback parserCallback = new HotseatParserCallback(
-                    hotseatTargetApps, hotseatItems, insertOperations, maxId + 1, myHotseatCount);
-            new HotseatLayoutParser(mContext,
-                    parserCallback).loadLayout(null, new IntArray());
-            mHotseatSize = hotseatItems.keyAt(hotseatItems.size() - 1) + 1;
-
-            if (!insertOperations.isEmpty()) {
-                mContext.getContentResolver().applyBatch(LauncherProvider.AUTHORITY,
-                        insertOperations);
-            }
-        }
-    }
-
-    private static String getPackage(Intent intent) {
-        return intent.getComponent() != null ? intent.getComponent().getPackageName()
-            : intent.getPackage();
-    }
-
-    /**
-     * Performs data import if possible.
-     * @return true on successful data import, false if it was not available
-     * @throws Exception if the import failed
-     */
-    public static boolean performImportIfPossible(Context context) throws Exception {
-        SharedPreferences devicePrefs = getDevicePrefs(context);
-        String sourcePackage = devicePrefs.getString(KEY_DATA_IMPORT_SRC_PKG, "");
-        String sourceAuthority = devicePrefs.getString(KEY_DATA_IMPORT_SRC_AUTHORITY, "");
-
-        if (TextUtils.isEmpty(sourcePackage) || TextUtils.isEmpty(sourceAuthority)) {
-            return false;
-        }
-
-        // Synchronously clear the migration flags. This ensures that we do not try migration
-        // again and thus prevents potential crash loops due to migration failure.
-        devicePrefs.edit().remove(KEY_DATA_IMPORT_SRC_PKG).remove(KEY_DATA_IMPORT_SRC_AUTHORITY).commit();
-
-        if (!Settings.call(context.getContentResolver(), Settings.METHOD_WAS_EMPTY_DB_CREATED)
-                .getBoolean(Settings.EXTRA_VALUE, false)) {
-            // Only migration if a new DB was created.
-            return false;
-        }
-
-        for (ProviderInfo info : context.getPackageManager().queryContentProviders(
-                null, context.getApplicationInfo().uid, 0)) {
-
-            if (sourcePackage.equals(info.packageName)) {
-                if ((info.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) == 0) {
-                    // Only migrate if the source launcher is also on system image.
-                    return false;
-                }
-
-                // Wait until we found a provider with matching authority.
-                if (sourceAuthority.equals(info.authority)) {
-                    if (TextUtils.isEmpty(info.readPermission) ||
-                            context.checkPermission(info.readPermission, Process.myPid(),
-                                    Process.myUid()) == PackageManager.PERMISSION_GRANTED) {
-                        // All checks passed, run the import task.
-                        return new ImportDataTask(context, sourceAuthority).importWorkspace();
-                    }
-                }
-            }
-        }
-        return false;
-    }
-
-    /**
-     * Extension of {@link DefaultLayoutParser} which only allows icons and shortcuts.
-     */
-    private static class HotseatLayoutParser extends DefaultLayoutParser {
-        public HotseatLayoutParser(Context context, LayoutParserCallback callback) {
-            super(context, null, callback, context.getResources(),
-                    LauncherAppState.getIDP(context).defaultLayoutId);
-        }
-
-        @Override
-        protected ArrayMap<String, TagParser> getLayoutElementsMap() {
-            // Only allow shortcut parsers
-            ArrayMap<String, TagParser> parsers = new ArrayMap<>();
-            parsers.put(TAG_FAVORITE, new AppShortcutWithUriParser());
-            parsers.put(TAG_SHORTCUT, new UriShortcutParser(mSourceRes));
-            parsers.put(TAG_RESOLVE, new ResolveParser());
-            return parsers;
-        }
-    }
-
-    /**
-     * {@link LayoutParserCallback} which adds items in empty hotseat spots.
-     */
-    private static class HotseatParserCallback implements LayoutParserCallback {
-        private final HashSet<String> mExistingApps;
-        private final IntSparseArrayMap<Object> mExistingItems;
-        private final ArrayList<ContentProviderOperation> mOutOps;
-        private final int mRequiredSize;
-        private int mStartItemId;
-
-        HotseatParserCallback(
-                HashSet<String> existingApps, IntSparseArrayMap<Object> existingItems,
-                ArrayList<ContentProviderOperation> outOps, int startItemId, int requiredSize) {
-            mExistingApps = existingApps;
-            mExistingItems = existingItems;
-            mOutOps = outOps;
-            mRequiredSize = requiredSize;
-            mStartItemId = startItemId;
-        }
-
-        @Override
-        public int generateNewItemId() {
-            return mStartItemId++;
-        }
-
-        @Override
-        public int insertAndCheck(SQLiteDatabase db, ContentValues values) {
-            if (mExistingItems.size() >= mRequiredSize) {
-                // No need to add more items.
-                return 0;
-            }
-            if (!Integer.valueOf(Favorites.CONTAINER_HOTSEAT)
-                    .equals(values.getAsInteger(Favorites.CONTAINER))) {
-                // Ignore items which are not for hotseat.
-                return 0;
-            }
-
-            Intent intent;
-            try {
-                intent = Intent.parseUri(values.getAsString(Favorites.INTENT), 0);
-            } catch (URISyntaxException e) {
-                return 0;
-            }
-            String pkg = getPackage(intent);
-            if (pkg == null || mExistingApps.contains(pkg)) {
-                // The item does not target an app or is already in hotseat.
-                return 0;
-            }
-            mExistingApps.add(pkg);
-
-            // find next vacant spot.
-            int screen = 0;
-            while (mExistingItems.get(screen) != null) {
-                screen++;
-            }
-            mExistingItems.put(screen, intent);
-            values.put(Favorites.SCREEN, screen);
-            mOutOps.add(ContentProviderOperation.newInsert(Favorites.CONTENT_URI).withValues(values).build());
-            return 0;
-        }
-    }
-}
diff --git a/src/com/android/launcher3/provider/LauncherDbUtils.java b/src/com/android/launcher3/provider/LauncherDbUtils.java
index 7e05a5a..6855bb1 100644
--- a/src/com/android/launcher3/provider/LauncherDbUtils.java
+++ b/src/com/android/launcher3/provider/LauncherDbUtils.java
@@ -16,84 +16,21 @@
 
 package com.android.launcher3.provider;
 
-import android.content.ContentValues;
 import android.content.Context;
 import android.database.Cursor;
-import android.database.DatabaseUtils;
 import android.database.sqlite.SQLiteDatabase;
 import android.os.Binder;
 import android.os.Process;
-import android.util.Log;
 
-import com.android.launcher3.LauncherAppState;
 import com.android.launcher3.LauncherSettings.Favorites;
 import com.android.launcher3.pm.UserCache;
 import com.android.launcher3.util.IntArray;
 
-import java.util.Locale;
-
 /**
  * A set of utility methods for Launcher DB used for DB updates and migration.
  */
 public class LauncherDbUtils {
 
-    private static final String TAG = "LauncherDbUtils";
-
-    /**
-     * Makes the first screen as screen 0 (if screen 0 already exists,
-     * renames it to some other number).
-     * If the first row of screen 0 is non empty, runs a 'lossy' GridMigrationTask to clear
-     * the first row. The items in the first screen are moved and resized but the carry-forward
-     * items are simply deleted.
-     */
-    public static boolean prepareScreenZeroToHostQsb(Context context, SQLiteDatabase db) {
-        try (SQLiteTransaction t = new SQLiteTransaction(db)) {
-            // Get the first screen
-            final int firstScreenId;
-            try (Cursor c = db.rawQuery(String.format(Locale.ENGLISH,
-                    "SELECT MIN(%1$s) from %2$s where %3$s = %4$d",
-                    Favorites.SCREEN, Favorites.TABLE_NAME, Favorites.CONTAINER,
-                    Favorites.CONTAINER_DESKTOP), null)) {
-
-                if (!c.moveToNext()) {
-                    // No update needed
-                    t.commit();
-                    return true;
-                }
-
-                firstScreenId = c.getInt(0);
-            }
-
-            if (firstScreenId != 0) {
-                // Rename the first screen to 0.
-                renameScreen(db, firstScreenId, 0);
-            }
-
-            // Check if the first row is empty
-            if (DatabaseUtils.queryNumEntries(db, Favorites.TABLE_NAME,
-                    "container = -100 and screen = 0 and cellY = 0") == 0) {
-                // First row is empty, no need to migrate.
-                t.commit();
-                return true;
-            }
-
-            new LossyScreenMigrationTask(context, LauncherAppState.getIDP(context), db)
-                    .migrateScreen0();
-            t.commit();
-            return true;
-        } catch (Exception e) {
-            Log.e(TAG, "Failed to update workspace size", e);
-            return false;
-        }
-    }
-
-    private static void renameScreen(SQLiteDatabase db, int oldScreen, int newScreen) {
-        String[] whereParams = new String[] { Integer.toString(oldScreen) };
-        ContentValues values = new ContentValues();
-        values.put(Favorites.SCREEN, newScreen);
-        db.update(Favorites.TABLE_NAME, values, "container = -100 and screen = ?", whereParams);
-    }
-
     public static IntArray queryIntArray(SQLiteDatabase db, String tableName, String columnName,
             String selection, String groupBy, String orderBy) {
         IntArray out = new IntArray();
diff --git a/src/com/android/launcher3/provider/LossyScreenMigrationTask.java b/src/com/android/launcher3/provider/LossyScreenMigrationTask.java
deleted file mode 100644
index c0111b9..0000000
--- a/src/com/android/launcher3/provider/LossyScreenMigrationTask.java
+++ /dev/null
@@ -1,98 +0,0 @@
-/*
- * Copyright (C) 2016 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.android.launcher3.provider;
-
-import android.content.ContentValues;
-import android.content.Context;
-import android.database.sqlite.SQLiteDatabase;
-import android.graphics.Point;
-
-import com.android.launcher3.InvariantDeviceProfile;
-import com.android.launcher3.LauncherSettings.Favorites;
-import com.android.launcher3.Utilities;
-import com.android.launcher3.Workspace;
-import com.android.launcher3.model.GridSizeMigrationTask;
-import com.android.launcher3.util.IntSparseArrayMap;
-
-import java.util.ArrayList;
-
-/**
- * An extension of {@link GridSizeMigrationTask} which migrates only one screen and
- * deletes all carry-forward items.
- */
-public class LossyScreenMigrationTask extends GridSizeMigrationTask {
-
-    private final IntSparseArrayMap<DbEntry> mOriginalItems;
-    private final IntSparseArrayMap<DbEntry> mUpdates;
-
-    protected LossyScreenMigrationTask(
-            Context context, InvariantDeviceProfile idp, SQLiteDatabase db) {
-        // Decrease the rows count by 1
-        super(context, db, getValidPackages(context), false /* usePreviewTable */,
-                new Point(idp.numColumns, idp.numRows + 1),
-                new Point(idp.numColumns, idp.numRows));
-
-        mOriginalItems = new IntSparseArrayMap<>();
-        mUpdates = new IntSparseArrayMap<>();
-    }
-
-    @Override
-    protected void update(DbEntry item) {
-        mUpdates.put(item.id, item.copy());
-    }
-
-    @Override
-    protected ArrayList<DbEntry> loadWorkspaceEntries(int screen) {
-        ArrayList<DbEntry> result = super.loadWorkspaceEntries(screen);
-        for (DbEntry entry : result) {
-            mOriginalItems.put(entry.id, entry.copy());
-
-            // Shift all items by 1 in y direction and mark them for update.
-            entry.cellY++;
-            mUpdates.put(entry.id, entry.copy());
-        }
-
-        return result;
-    }
-
-    public void migrateScreen0() {
-        migrateScreen(Workspace.FIRST_SCREEN_ID);
-
-        ContentValues tempValues = new ContentValues();
-        for (DbEntry update : mUpdates) {
-            DbEntry org = mOriginalItems.get(update.id);
-
-            if (org.cellX != update.cellX || org.cellY != update.cellY
-                    || org.spanX != update.spanX || org.spanY != update.spanY) {
-                tempValues.clear();
-                update.addToContentValues(tempValues);
-                mDb.update(Favorites.TABLE_NAME, tempValues, "_id = ?",
-                        new String[] {Integer.toString(update.id)});
-            }
-        }
-
-        // Delete any carry over items as we are only migration a single screen.
-        for (DbEntry entry : mCarryOver) {
-            mEntryToRemove.add(entry.id);
-        }
-
-        if (!mEntryToRemove.isEmpty()) {
-            mDb.delete(Favorites.TABLE_NAME,
-                    Utilities.createDbSelectionQuery(Favorites._ID, mEntryToRemove), null);
-        }
-    }
-}