FRAME: Unity Balance Conversion for Different IDs of Native Asset (#3659)

Introduce types to define 1:1 balance conversion for different relative
asset ids/locations of native asset.

Examples:
native asset on Asset Hub presented as `VersionedLocatableAsset` type in
the context of Relay Chain is
```
{
  `location`: (0, Parachain(1000)),
  `asset_id`: (1, Here),
}
```
and it's balance should be converted 1:1 by implementations of
`ConversionToAssetBalance` trait.

---------

Co-authored-by: Branislav Kontur <bkontur@gmail.com>

polkadot/runtime/rococo/src/lib.rs

@@ -25,7 +25,10 @@ use beefy_primitives::{
 	ecdsa_crypto::{AuthorityId as BeefyId, Signature as BeefySignature},
 	mmr::{BeefyDataProvider, MmrLeafVersion},
 };
-use frame_support::dynamic_params::{dynamic_pallet_params, dynamic_params};
+use frame_support::{
+	dynamic_params::{dynamic_pallet_params, dynamic_params},
+	traits::FromContains,
+};
 use pallet_nis::WithMaximumOf;
 use parity_scale_codec::{Decode, Encode, MaxEncodedLen};
 use primitives::{
@@ -40,7 +43,8 @@ use rococo_runtime_constants::system_parachain::BROKER_ID;
 use runtime_common::{
 	assigned_slots, auctions, claims, crowdloan, identity_migrator, impl_runtime_weights,
 	impls::{
-		LocatableAssetConverter, ToAuthor, VersionedLocatableAsset, VersionedLocationConverter,
+		ContainsParts, LocatableAssetConverter, ToAuthor, VersionedLocatableAsset,
+		VersionedLocationConverter,
 	},
 	paras_registrar, paras_sudo_wrapper, prod_or_fast, slots,
 	traits::{Leaser, OnSwap},
@@ -74,10 +78,10 @@ use frame_support::{
 	genesis_builder_helper::{build_state, get_preset},
 	parameter_types,
 	traits::{
-		fungible::HoldConsideration, Contains, EitherOf, EitherOfDiverse, EnsureOrigin,
-		EnsureOriginWithArg, EverythingBut, InstanceFilter, KeyOwnerProofSystem,
-		LinearStoragePrice, PrivilegeCmp, ProcessMessage, ProcessMessageError, StorageMapShim,
-		WithdrawReasons,
+		fungible::HoldConsideration, tokens::UnityOrOuterConversion, Contains, EitherOf,
+		EitherOfDiverse, EnsureOrigin, EnsureOriginWithArg, EverythingBut, InstanceFilter,
+		KeyOwnerProofSystem, LinearStoragePrice, PrivilegeCmp, ProcessMessage, ProcessMessageError,
+		StorageMapShim, WithdrawReasons,
 	},
 	weights::{ConstantMultiplier, WeightMeter, WeightToFee as _},
 	PalletId,
@@ -87,7 +91,7 @@ use pallet_grandpa::{fg_primitives, AuthorityId as GrandpaId};
 use pallet_identity::legacy::IdentityInfo;
 use pallet_session::historical as session_historical;
 use pallet_transaction_payment::{FeeDetails, FungibleAdapter, RuntimeDispatchInfo};
-use sp_core::{ConstU128, OpaqueMetadata, H256};
+use sp_core::{ConstU128, ConstU8, OpaqueMetadata, H256};
 use sp_runtime::{
 	create_runtime_str, generic, impl_opaque_keys,
 	traits::{
@@ -523,7 +527,15 @@ impl pallet_treasury::Config for Runtime {
 		LocatableAssetConverter,
 		VersionedLocationConverter,
 	>;
-	type BalanceConverter = AssetRate;
+	type BalanceConverter = UnityOrOuterConversion<
+		ContainsParts<
+			FromContains<
+				xcm_builder::IsChildSystemParachain<ParaId>,
+				xcm_builder::IsParentsOnly<ConstU8<1>>,
+			>,
+		>,
+		AssetRate,
+	>;
 	type PayoutPeriod = PayoutSpendPeriod;
 	#[cfg(feature = "runtime-benchmarks")]
 	type BenchmarkHelper = runtime_common::impls::benchmarks::TreasuryArguments;