Created metric events for scoped directory access API.

BUG: 27334821
Change-Id: I8a1bfc328dcd26b42bb66884d14b34ad11aa232f
diff --git a/core/java/android/os/Environment.java b/core/java/android/os/Environment.java
index 1085b1e..2410503 100644
--- a/core/java/android/os/Environment.java
+++ b/core/java/android/os/Environment.java
@@ -493,7 +493,7 @@
      * </ul>
      * @hide
      */
-    private static final String[] STANDARD_DIRECTORIES = {
+    public static final String[] STANDARD_DIRECTORIES = {
             DIRECTORY_MUSIC,
             DIRECTORY_PODCASTS,
             DIRECTORY_RINGTONES,