message: Properly set AllocationDescription for tensors that are allocated by generated kernels.
  Otherwise, allocation tracing and in particular the python timeline module does not work.
diff: @@ -41,7 +41,20 @@ class MlirTensorBuffer : public TensorBuffer {
  TensorBuffer* root_buffer() override { return this; }
  void FillAllocationDescription(AllocationDescription* proto) const override {
  - proto->set_allocated_bytes(size_);
  + proto->set_requested_bytes(static_cast<int64>(size_));
  + proto->set_allocator_name(allocator_->Name());
  + proto->set_ptr(reinterpret_cast<uintptr_t>(data()));
  + if (allocator_->TracksAllocationSizes()) {
  + auto ab = static_cast<int64>(allocator_->AllocatedSize(data()));
  + proto->set_allocated_bytes(ab);
  + int64 id = allocator_->AllocationId(data());
  + if (id > 0) {
  + proto->set_allocation_id(id);
  + }
  + if (RefCountIsOne()) {
  + proto->set_has_single_reference(true);
  + }
  + }
  }
  private:
  