Re-add the progress bar for storage preferences.

This re-adds the progress bar and unifies the
StorageItemPreference and its alternate.

Change-Id: Iefc12b4b554306c706c83be232175dd2b84227b7
Fixes: 36223433
Test: Settings robotest

tests/robotests/src/com/android/settings/TestUtils.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2017 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.settings;
+
+/**
+ * Convenience methods and constants for testing.
+ */
+public class TestUtils {
+    public static final long KILOBYTE = 1024L; // TODO: Change to 1000 in O Robolectric.
+    public static final long MEGABYTE = KILOBYTE * KILOBYTE;
+    public static final long GIGABYTE = KILOBYTE * MEGABYTE;
+}