vold: Use separate flag for wrappedkey

Use a separate fstab flag for wrappedkey
support rather than file_contents_mode.

CRs-Fixed: 2316112

Change-Id: I4972514cdfc8e17abf1fca777cae39fb7a2e19a8
diff --git a/Ext4Crypt.cpp b/Ext4Crypt.cpp
index 4432a21..4b3aeb3 100644
--- a/Ext4Crypt.cpp
+++ b/Ext4Crypt.cpp
@@ -199,25 +199,9 @@
     return false;
 }
 
-static bool is_wrapped_key_supported_common(const std::string& mount_point) {
-    struct fstab_rec* rec = fs_mgr_get_entry_for_mount_point(fstab_default, mount_point);
-    char const* contents_mode = NULL;
-    char const* filenames_mode = NULL;
-
-    fs_mgr_get_file_encryption_modes(rec, &contents_mode, &filenames_mode);
-    if (!contents_mode || !filenames_mode) {
-        LOG(ERROR) << "Couldn't read file or contents mode, returning false";
-        return false;
-    }
-
-    if (strcmp(contents_mode, "ice_wrapped_key_supported") == 0)
-        return true;
-    else
-        return false;
-}
-
 bool is_wrapped_key_supported() {
-    return is_wrapped_key_supported_common(DATA_MNT_POINT);
+    return fs_mgr_is_wrapped_key_supported(
+        fs_mgr_get_entry_for_mount_point(fstab_default, DATA_MNT_POINT));
 }
 
 bool is_wrapped_key_supported_external() {