sdk: add support for --skip-chroot-upgrade

BUG=b:217247914
TEST=unit tests

Change-Id: Ied049312f7ab82484d165e857a8f51eccf787790
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/3723161
Reviewed-by: Alex Klein <saklein@chromium.org>
Reviewed-by: Benjamin Shai <bshai@google.com>
Tested-by: Jack Neus <jackneus@google.com>
Commit-Queue: Jack Neus <jackneus@google.com>
Reviewed-by: Sergey Frolov <sfrolov@google.com>
Reviewed-by: Madeleine Hardt <hardtmad@google.com>
diff --git a/api/controller/sdk.py b/api/controller/sdk.py
index 06e4182..a02bb92 100644
--- a/api/controller/sdk.py
+++ b/api/controller/sdk.py
@@ -41,6 +41,7 @@
   chroot_path = input_proto.chroot.path
   cache_dir = input_proto.chroot.cache_dir
   sdk_version = input_proto.sdk_version
+  skip_chroot_upgrade = input_proto.skip_chroot_upgrade
 
   if chroot_path and not os.path.isabs(chroot_path):
     cros_build_lib.Die('The chroot path must be absolute.')
@@ -54,7 +55,8 @@
       use_image=use_image,
       cache_dir=cache_dir,
       chroot_path=chroot_path,
-      sdk_version=sdk_version)
+      sdk_version=sdk_version,
+      skip_chroot_upgrade=skip_chroot_upgrade)
 
   version = sdk.Create(args)