Deprecate cros_build_lib.{To,From}ChrootPath().

BUG=brillo:1032
TEST=cbuildbot/run_tests
TEST=Trybot

Change-Id: I7403d5af1ddea24ee8caaec648c7c52f83878c73
Reviewed-on: https://chromium-review.googlesource.com/269266
Reviewed-by: Bertrand Simonnet <bsimonnet@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
diff --git a/cli/flash.py b/cli/flash.py
index 11931d7..fdc9c2b 100644
--- a/cli/flash.py
+++ b/cli/flash.py
@@ -22,12 +22,13 @@
 from chromite.lib import dev_server_wrapper as ds_wrapper
 from chromite.lib import operation
 from chromite.lib import osutils
+from chromite.lib import path_util
 from chromite.lib import project_sdk
 from chromite.lib import remote_access
 from chromite.lib import workspace_lib
 
 
-_DEVSERVER_STATIC_DIR = cros_build_lib.FromChrootPath(
+_DEVSERVER_STATIC_DIR = path_util.FromChrootPath(
     os.path.join(constants.CHROOT_SOURCE_ROOT, 'devserver', 'static'))
 
 
@@ -347,7 +348,7 @@
       clobber: Clobber stateful partition (defaults to False).
     """
     # Copy latest stateful_update to device.
-    stateful_update_bin = cros_build_lib.FromChrootPath(
+    stateful_update_bin = path_util.FromChrootPath(
         self.STATEFUL_UPDATE_BIN)
     device.CopyToWorkDir(stateful_update_bin)
     msg = 'Updating stateful partition'