Parcelable objects for Disk/Volume.

Will eventually be used by SystemUI and/or Settings.

Also fix SettingsProvider NPE.

Bug: 19993667, 19909433
Change-Id: Ie326849ac5f43ee35f728d9cc0e332b72292db70
diff --git a/core/java/android/os/Environment.java b/core/java/android/os/Environment.java
index 2db976e..2eb97f1 100644
--- a/core/java/android/os/Environment.java
+++ b/core/java/android/os/Environment.java
@@ -80,11 +80,11 @@
 
         public File[] getExternalDirs() {
             final StorageVolume[] volumes = StorageManager.getVolumeList(mUserId);
-            final File[] dirs = new File[volumes.length];
+            final File[] files = new File[volumes.length];
             for (int i = 0; i < volumes.length; i++) {
-                dirs[i] = volumes[i].getPathFile();
+                files[i] = volumes[i].getPathFile();
             }
-            return dirs;
+            return files;
         }
 
         @Deprecated