message: Pass stats_collector when using SymbolicGradientOp.
diff: @@ -240,6 +240,7 @@ class SymbolicGradientOp : public AsyncOpKernel {
  opts.rendezvous = ctx->rendezvous();
  opts.cancellation_manager = ctx->cancellation_manager();
  opts.runner = ctx->runner();
  + opts.stats_collector = ctx->stats_collector();
  std::vector<Tensor> args;
  args.reserve(ctx->num_inputs());
  for (int i = 0; i < ctx->num_inputs(); ++i) {
  