diff --git a/services/core/java/com/android/server/am/RecentTasks.java b/services/core/java/com/android/server/am/RecentTasks.java
index 91f2aa8fe4f94..fb1cda7edb544 100644
--- a/services/core/java/com/android/server/am/RecentTasks.java
+++ b/services/core/java/com/android/server/am/RecentTasks.java
@@ -37,10 +37,7 @@ import android.content.pm.PackageManager;
 import android.graphics.Bitmap;
 import android.os.Environment;
 import android.os.RemoteException;
-import android.os.SystemClock;
 import android.os.UserHandle;
-import android.provider.Settings.System;
-import android.util.ArraySet;
 import android.util.Slog;
 import android.util.SparseArray;
 import android.util.SparseBooleanArray;
diff --git a/services/core/java/com/android/server/am/TaskPersister.java b/services/core/java/com/android/server/am/TaskPersister.java
index 11fd3bc61ca67..ceb7db6b85235 100644
--- a/services/core/java/com/android/server/am/TaskPersister.java
+++ b/services/core/java/com/android/server/am/TaskPersister.java
@@ -88,6 +88,7 @@ public class TaskPersister {
     private final ActivityStackSupervisor mStackSupervisor;
     private final RecentTasks mRecentTasks;
     private final SparseArray<SparseBooleanArray> mTaskIdsInFile = new SparseArray<>();
+    private final File mTaskIdsDir;
 
     /**
      * Value determines write delay mode as follows: < 0 We are Flushing. No delays between writes
@@ -139,12 +140,22 @@ public class TaskPersister {
             }
         }
 
+        mTaskIdsDir = new File(Environment.getDataDirectory(), "system_de");
         mStackSupervisor = stackSupervisor;
         mService = service;
         mRecentTasks = recentTasks;
         mLazyTaskWriterThread = new LazyTaskWriterThread("LazyTaskWriterThread");
     }
 
+    @VisibleForTesting
+    TaskPersister(File workingDir) {
+        mTaskIdsDir = workingDir;
+        mStackSupervisor = null;
+        mService = null;
+        mRecentTasks = null;
+        mLazyTaskWriterThread = new LazyTaskWriterThread("LazyTaskWriterThreadTest");
+    }
+
     void startPersisting() {
         if (!mLazyTaskWriterThread.isAlive()) {
             mLazyTaskWriterThread.start();
@@ -207,8 +218,8 @@ public class TaskPersister {
         return persistedTaskIds.clone();
     }
 
-    private void maybeWritePersistedTaskIdsForUser(@NonNull SparseBooleanArray taskIds,
-            int userId) {
+    @VisibleForTesting
+    void maybeWritePersistedTaskIdsForUser(@NonNull SparseBooleanArray taskIds, int userId) {
         if (userId < 0) {
             return;
         }
@@ -565,8 +576,12 @@ public class TaskPersister {
         return BitmapFactory.decodeFile(filename);
     }
 
-    static File getUserPersistedTaskIdsFile(int userId) {
-        return new File(Environment.getDataSystemDeDirectory(userId), PERSISTED_TASK_IDS_FILENAME);
+    private File getUserPersistedTaskIdsFile(int userId) {
+        File userTaskIdsDir = new File(mTaskIdsDir, String.valueOf(userId));
+        if (!userTaskIdsDir.exists() && !userTaskIdsDir.mkdirs()) {
+            Slog.e(TAG, "Error while creating user directory: " + userTaskIdsDir);
+        }
+        return new File(userTaskIdsDir, PERSISTED_TASK_IDS_FILENAME);
     }
 
     static File getUserTasksDir(int userId) {
diff --git a/services/tests/servicestests/src/com/android/server/am/TaskPersisterTest.java b/services/tests/servicestests/src/com/android/server/am/TaskPersisterTest.java
new file mode 100644
index 0000000000000..e440a0d603d22
--- /dev/null
+++ b/services/tests/servicestests/src/com/android/server/am/TaskPersisterTest.java
@@ -0,0 +1,85 @@
+/*
+ * 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.server.am;
+
+import android.content.pm.UserInfo;
+import android.os.Environment;
+import android.os.UserHandle;
+import android.os.UserManager;
+import android.test.AndroidTestCase;
+import android.util.Log;
+import android.util.SparseBooleanArray;
+
+import com.android.server.am.TaskPersister;
+
+import java.io.File;
+import java.util.Random;
+
+public class TaskPersisterTest extends AndroidTestCase {
+    private static final String TEST_USER_NAME = "AM-Test-User";
+
+    private TaskPersister mTaskPersister;
+    private int testUserId;
+    private UserManager mUserManager;
+
+    @Override
+    public void setUp() throws Exception {
+        super.setUp();
+        mUserManager = UserManager.get(getContext());
+        mTaskPersister = new TaskPersister(getContext().getFilesDir());
+        testUserId = createUser(TEST_USER_NAME, 0);
+    }
+
+    @Override
+    public void tearDown() throws Exception {
+        super.tearDown();
+        mTaskPersister.unloadUserDataFromMemory(testUserId);
+        removeUser(testUserId);
+    }
+
+    private int getRandomTaskIdForUser(int userId) {
+        int taskId = (int) (Math.random() * UserHandle.PER_USER_RANGE);
+        taskId += UserHandle.PER_USER_RANGE * userId;
+        return taskId;
+    }
+
+    public void testTaskIdsPersistence() {
+        SparseBooleanArray taskIdsOnFile = mTaskPersister.loadPersistedTaskIdsForUser(testUserId);
+        for (int i = 0; i < 100; i++) {
+            taskIdsOnFile.put(getRandomTaskIdForUser(testUserId), true);
+        }
+        mTaskPersister.maybeWritePersistedTaskIdsForUser(taskIdsOnFile, testUserId);
+        SparseBooleanArray newTaskIdsOnFile = mTaskPersister
+                .loadPersistedTaskIdsForUser(testUserId);
+        assertTrue("TaskIds written differ from TaskIds read back from file",
+                taskIdsOnFile.equals(newTaskIdsOnFile));
+    }
+
+    private int createUser(String name, int flags) {
+        UserInfo user = mUserManager.createUser(name, flags);
+        if (user == null) {
+            fail("Error while creating the test user: " + TEST_USER_NAME);
+        }
+        return user.id;
+    }
+
+    private void removeUser(int userId) {
+        if (!mUserManager.removeUser(userId)) {
+            fail("Error while removing the test user: " + TEST_USER_NAME);
+        }
+    }
+}
\ No newline at end of file