message: Add accessor for aliased indices.
diff: @@ -105,6 +105,8 @@ class ExecutionInput {
  unowned_indices_.erase(index);
  }
  + const std::set<ShapeIndex>& unowned_indices() { return unowned_indices_; }
  +
  const ShapeTree<MaybeOwningDeviceMemory>& Buffers() const { return buffers_; }
  ShapeTree<MaybeOwningDeviceMemory>* MutableBuffers() { return &buffers_; }
  @@ -190,6 +192,12 @@ class ExecutionOutput {
  return std::move(to_be_released_);
  }
  + std::vector<ShapeIndex> ConsumeAliasedIndices() {
  + auto aliased = std::move(aliased_indices_);
  + aliased_indices_.clear();
  + return aliased;
  + }
  +
  private:
  ScopedShapedBuffer result_;
  