message: TpuDriver: Add client_version field to provide better feedback in the event of
  non-backwards-compatible protocol changes.
diff: @@ -21,6 +21,8 @@ import "tensorflow/compiler/xla/python/tpu_driver/tpu_driver.proto";
  import "tensorflow/compiler/xla/service/hlo.proto";
  import "tensorflow/compiler/xla/xla_data.proto";
  +option optimize_for = SPEED;
  +
  message StatusMessage {
  required int32 code = 1;
  optional string message = 2;
  @@ -134,10 +136,15 @@ message StreamResponse {
  repeated Entry entry = 20;
  }
  -message OpenRequest {}
  +message OpenRequest {
  + // The version number for this client. Versions are bumped in case of
  + // backwards incompatible client-server protocol changes. Servers will reject
  + // clients with an unsupported version.
  + optional int32 client_version = 1 [default = 0];
  +}
  message OpenResponse {
  - required fixed32 client_id = 1;
  + required uint32 client_id = 1;
  // Maximum time this client can be idle before it is GC'ed and all resources
  // released.
  