Shift around encryption public APIs.

There are far too many Context APIs with special directory paths
to replicate device-encryption versions of them all.  Instead, add
methods to clone a Context that explicitly stores its data in either
credential- or device-encrypted storage.

Methods to test the behavior of a given Context.

Bug: 22358539
Change-Id: I6a6290a9b282605ce9a1f82742fc2c4c50536754
diff --git a/core/java/android/content/pm/ApplicationInfo.java b/core/java/android/content/pm/ApplicationInfo.java
index 545478c..4816734 100644
--- a/core/java/android/content/pm/ApplicationInfo.java
+++ b/core/java/android/content/pm/ApplicationInfo.java
@@ -591,13 +591,21 @@
     public String[] sharedLibraryFiles;
     
     /**
-     * Full path to a directory assigned to the package for its persistent data.
+     * Full path to the default directory assigned to the package for its
+     * persistent data.
      */
     public String dataDir;
 
-    /** {@hide} */
+    /**
+     * Full path to the device-encrypted directory assigned to the package for
+     * its persistent data.
+     */
     public String deviceEncryptedDataDir;
-    /** {@hide} */
+
+    /**
+     * Full path to the credential-encrypted directory assigned to the package
+     * for its persistent data.
+     */
     public String credentialEncryptedDataDir;
 
     /**