Add Context.getNoBackupFilesDir()

This is an app-private filesystem space exactly like the one
reported by Context.getFilesDir(), with one exception:  files
placed here are never backed up by the full-backup infrastructure.
If an app attempts to back up any of its contents via the normal
API it's immediately ignored with a logged warning.

The restriction is also enforced on the restore side, because
apps using support libraries might wind up creating full backup
archives containing no_backup subdirs on pre-L devices (via
adb backup, Helium, &c.).  We check for this before passing the
restore data to the app, and drop it if we detect the situation
so that the app never sees the bits.

Bug 16240573

Change-Id: I11216a391f1d32117ec7ce15aafc9cd93d0337de

1 files changed, 6 insertions, 1 deletions

diff --git a/core/java/android/content/ContextWrapper.java b/core/java/android/content/ContextWrapper.java
index dbf9122..13eed07 100644
--- a/core/java/android/content/ContextWrapper.java
+++ b/core/java/android/content/ContextWrapper.java
@@ -200,7 +200,12 @@ public class ContextWrapper extends Context {
     public File getFilesDir() {
         return mBase.getFilesDir();
     }
-    
+
+    @Override
+    public File getNoBackupFilesDir() {
+        return mBase.getNoBackupFilesDir();
+    }
+
     @Override
     public File getExternalFilesDir(String type) {
         return mBase.getExternalFilesDir(type);