lxc: Stop exporting base_image.BaseImage

It is a class only used internally

BUG=chromium:1103904
TEST=./utils/unittest_suite.py -r site_utils/lxc

Change-Id: I915ebf2070bf4ab6ec78e1795ea9f309f61746ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2293145
Commit-Queue: Prathmesh Prabhu <[email protected]>
Tested-by: Prathmesh Prabhu <[email protected]>
Reviewed-by: Sean Abraham <[email protected]>
diff --git a/site_utils/lxc.py b/site_utils/lxc.py
index 8595163..4ff0b65 100755
--- a/site_utils/lxc.py
+++ b/site_utils/lxc.py
@@ -17,6 +17,7 @@
 import common
 from autotest_lib.client.bin import utils
 from autotest_lib.site_utils import lxc
+from autotest_lib.site_utils.lxc import base_image
 
 
 def parse_options():
@@ -41,8 +42,8 @@
     options = parser.parse_args()
     if not options.setup and not options.force_delete:
         raise argparse.ArgumentError(
-                'Use --setup to setup a base container, or --force_delete to '
-                'delete all containers in given path.')
+            'Use --setup to setup a base container, or --force_delete to '
+            'delete all containers in given path.')
     return options
 
 
@@ -57,7 +58,7 @@
         utils.run('sudo true')
 
     options = parse_options()
-    image = lxc.BaseImage(container_path=options.path)
+    image = base_image.BaseImage(container_path=options.path)
     if options.setup:
         image.setup(name=options.name, force_delete=options.force_delete)
     elif options.force_delete: