message: Remove superfluous ref/unref.  We assume AsyncOpKernel outlives its done callback.
diff: @@ -103,7 +103,6 @@ class CollectiveOpV1Kernel : public AsyncOpKernel {
  // This is the first invocation: Finish initializing col_params_.
  // Schedule the `CompleteParamsAsync` call on a work queue that can handle
  // blocking work because it's not guaranteed that this call cannot block.
  - col_params_->Ref();
  c->collective_executor()->RunClosure([this, c, col_exec, done]() {
  VLOG(1) << "CollectiveOpKernel CompleteParams for collective "
  << col_params_->name << " device " << c->device()->name()
  @@ -112,7 +111,6 @@ class CollectiveOpV1Kernel : public AsyncOpKernel {
  col_exec->CompleteParamsAsync(
  c->device()->attributes(), col_params_, c->cancellation_manager(),
  [this, c, done](const Status& s) {
  - core::ScopedUnref unref(col_params_);
  if (s.ok()) {
  col_params_->instance.impl_details.dependencies = dependencies_;
  ComputeAsync(c, done);
  