binhost: add support for saving multiple binhost files.

BUG=b:241593955
TEST=run_tests.py

Change-Id: I53f85cd64e48f32ab2aae3c7c14e54059c245d68
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/3966771
Tested-by: Arif Kasim <arifkasim@google.com>
Reviewed-by: Alex Klein <saklein@chromium.org>
Commit-Queue: Arif Kasim <arifkasim@google.com>
diff --git a/api/controller/binhost.py b/api/controller/binhost.py
index 3f230d8..005831e 100644
--- a/api/controller/binhost.py
+++ b/api/controller/binhost.py
@@ -31,6 +31,9 @@
     binhost_pb2.OVERLAYTYPE_NONE: None,
 }
 
+# Default maximum number of URIs to be stored in Binhost conf file.
+_DEFAULT_BINHOST_MAX_URIS = 1
+
 
 def _GetBinhostsResponse(_input_proto, output_proto, _config):
     """Add fake binhosts to a successful response."""
@@ -250,9 +253,10 @@
     key = binhost_pb2.BinhostKey.Name(input_proto.key)
     uri = input_proto.uri
     private = input_proto.private
+    max_uris = input_proto.max_uris or _DEFAULT_BINHOST_MAX_URIS
 
     output_proto.output_file = binhost.SetBinhost(
-        target, key, uri, private=private
+        target, key, uri, private=private, max_uris=max_uris
     )