SdkService/Uprev: Request source root, not chroot

Compiled BAPI protos to incorporate https://crrev.com/c/4374071.
Updated the SDK Uprev endpoint stub to stop referencing the chroot.
More meaningful logic will come in follow-on CLs.

BUG=b:259445595
TEST=./run_tests

Cq-Depend: chromium:4374071
Change-Id: Ib75b47c8109f35fa50aeb6920b616c5f39a58484
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4375639
Commit-Queue: Greg Edelston <gredelston@google.com>
Tested-by: Greg Edelston <gredelston@google.com>
Reviewed-by: Cindy Lin <xcl@google.com>
diff --git a/api/controller/sdk.py b/api/controller/sdk.py
index 7dc489c..0fb9dda 100644
--- a/api/controller/sdk.py
+++ b/api/controller/sdk.py
@@ -5,6 +5,7 @@
 """SDK chroot operations."""
 
 import os
+import pathlib
 from typing import Dict, Union
 
 from chromite.api import controller
@@ -179,14 +180,14 @@
 
 
 @faux.all_empty
-@validate.require("chroot")
+@validate.require("source_root")
 @validate.require("binhost_gs_bucket")
 @validate.validation_complete
 def Uprev(input_proto, output_proto, _config):
     """Update the SDK version and prebuilt files to point to the latest SDK."""
     target_version = input_proto.version or sdk.GetLatestVersion()
     modified_files = sdk.UprevSdkAndPrebuilts(
-        controller_util.ParseChroot(input_proto.chroot),
+        pathlib.Path(input_proto.source_root.path),
         binhost_gs_bucket=input_proto.binhost_gs_bucket,
         version=target_version,
     )