Create a new mount mode for installer packages.

New external storage mount mode for installers so
that they can access obb dirs of all apps.

Bug: 111789719
Test: atest android.appsecurity.cts#testExternalStorageObbGifts
Change-Id: Ifab3c0702a431d542a6a3ae82ca8b67d9fcd7506
diff --git a/core/java/com/android/internal/os/Zygote.java b/core/java/com/android/internal/os/Zygote.java
index 65213c0..65b9fad 100644
--- a/core/java/com/android/internal/os/Zygote.java
+++ b/core/java/com/android/internal/os/Zygote.java
@@ -81,6 +81,11 @@
     public static final int MOUNT_EXTERNAL_READ = IVold.REMOUNT_MODE_READ;
     /** Read-write external storage should be mounted. */
     public static final int MOUNT_EXTERNAL_WRITE = IVold.REMOUNT_MODE_WRITE;
+    /**
+     * Mount mode for package installers which should give them access to
+     * all obb dirs in addition to their package sandboxes
+     */
+    public static final int MOUNT_EXTERNAL_INSTALLER = IVold.REMOUNT_MODE_INSTALLER;
     /** Read-write external storage should be mounted instead of package sandbox */
     public static final int MOUNT_EXTERNAL_FULL = IVold.REMOUNT_MODE_FULL;