[protosync] Server-side -> client

Sync server-side changes from
https://critique.corp.google.com/#review/251735875 to client.

Bug: None
Change-Id: I946bf7baeabfcd57575942493d363ec81efef155
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1660853
Commit-Queue: Jit Yao Yap <jityao@google.com>
Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Auto-Submit: Jit Yao Yap <jityao@google.com>
Cr-Commit-Position: refs/heads/master@{#669633}

components/policy/proto/device_management_backend.proto

@@ -180,6 +180,12 @@ message DeviceRegisterRequest {
   // The date the device was manufactured in yyyy-mm-dd format.
   // This field might be set only if register type == DEVICE.
   optional string manufacture_date = 16;
+
+  // Currently using in token enrollment to ensure domain in request matches
+  // domain from token.
+  optional string expected_enrollment_domain = 17;
+
+  // Next id: 18.
 }
 
 // Response from server to device register request.