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: Iab112f0273806f8f812f14d6691bbe71dff42d83
diff --git a/VolumeManager.h b/VolumeManager.h
index 9e990d0..b1aa954 100644
--- a/VolumeManager.h
+++ b/VolumeManager.h
@@ -171,6 +171,8 @@
                             const std::string& packageName, const char* dirName);
     int destroySandboxForAppOnVol(const std::string& packageName, const std::string& sandboxId,
                                   userid_t userId, const std::string& volLabel);
+    int getMountModeForRunningProc(const std::vector<std::string>& packagesForUid, userid_t userId,
+                                   struct stat& mntWriteStat);
 
     void handleDiskAdded(const std::shared_ptr<android::vold::Disk>& disk);
     void handleDiskChanged(dev_t device);