Allow factory reset without PERSISTENT_DATA_BLOCK_SERVICE

Currently factory reset action is ignored if
PERSISTENT_DATA_BLOCK_SERVICE isn't presented on device.
Make sure that we can execute regular factory reset without
it by utilizing the logic from shouldWipePersistentDataBlock.

Test: manual verify on aosp build
Bug: 129137473
Bug: 196634851
Change-Id: I2abcb93cbc0872dd920c1dd62152596ddd723691
Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>

Author: dimorinny

src/com/android/settings/MainClearConfirm.java

@@ -86,13 +86,14 @@ public void onClick(View v) {
                 return;
             }
 
+            final PersistentDataBlockManager pdbManager;
             // pre-flight check hardware support PersistentDataBlockManager
-            if (SystemProperties.get(PERSISTENT_DATA_BLOCK_PROP).equals("")) {
-                return;
-            }
-
-            final PersistentDataBlockManager pdbManager = (PersistentDataBlockManager)
+            if (!SystemProperties.get(PERSISTENT_DATA_BLOCK_PROP).equals("")) {
+                pdbManager = (PersistentDataBlockManager)
                     getActivity().getSystemService(Context.PERSISTENT_DATA_BLOCK_SERVICE);
+            } else {
+                pdbManager = null;
+            }
 
             if (shouldWipePersistentDataBlock(pdbManager)) {