Build API: Enter chroot on INSIDE assertion.

BUG=chromium:953049
TEST=run_tests
TEST=manual - called INSIDE endpoint and verified entry
Cq-Depend: chromium:1569042

Change-Id: I78ad1a249d90b5de112ed6da4db319bcf19ff836
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1570352
Tested-by: Alex Klein <saklein@chromium.org>
Reviewed-by: Evan Hernandez <evanhernandez@chromium.org>
Reviewed-by: Sean Abraham <seanabraham@chromium.org>
diff --git a/api/controller/sdk.py b/api/controller/sdk.py
index 25ec2bf..dabb0f8 100644
--- a/api/controller/sdk.py
+++ b/api/controller/sdk.py
@@ -24,15 +24,13 @@
   bootstrap = input_proto.flags.bootstrap
   use_image = not input_proto.flags.no_use_image
 
-  chrome_root = input_proto.paths.chrome
-  cache_dir = input_proto.paths.cache
-  chroot_path = input_proto.paths.chroot
+  chroot_path = input_proto.chroot.path
+  cache_dir = input_proto.chroot.cache_dir
 
   if chroot_path and not os.path.isabs(chroot_path):
     cros_build_lib.Die('The chroot path must be absolute.')
 
-  paths = sdk.ChrootPaths(cache_dir=cache_dir, chrome_root=chrome_root,
-                          chroot_path=chroot_path)
+  paths = sdk.ChrootPaths(cache_dir=cache_dir, chroot_path=chroot_path)
   args = sdk.CreateArguments(replace=replace, bootstrap=bootstrap,
                              use_image=use_image, paths=paths)