Remove unused parent_hash in OverlayedChanges::into_storage_changes (#11011)

Ref https://github.com/paritytech/substrate/pull/10922#issuecomment-1064258443

CC @cheme

substrate/primitives/state-machine/src/ext.rs

@@ -660,7 +660,6 @@ where
 		self.overlay
 			.drain_storage_changes(
 				self.backend,
-				Default::default(),
 				self.storage_transaction_cache,
 				Default::default(), // using any state
 			)
@@ -680,12 +679,7 @@ where
 		}
 		let changes = self
 			.overlay
-			.drain_storage_changes(
-				self.backend,
-				Default::default(),
-				self.storage_transaction_cache,
-				state_version,
-			)
+			.drain_storage_changes(self.backend, self.storage_transaction_cache, state_version)
 			.expect(EXT_NOT_ALLOWED_TO_FAIL);
 		self.backend
 			.commit(

substrate/primitives/state-machine/src/overlayed_changes/mod.rs

@@ -500,21 +500,19 @@ impl OverlayedChanges {
 	pub fn into_storage_changes<B: Backend<H>, H: Hasher>(
 		mut self,
 		backend: &B,
-		parent_hash: H::Out,
 		mut cache: StorageTransactionCache<B::Transaction, H>,
 		state_version: StateVersion,
 	) -> Result<StorageChanges<B::Transaction, H>, DefaultError>
 	where
 		H::Out: Ord + Encode + 'static,
 	{
-		self.drain_storage_changes(backend, parent_hash, &mut cache, state_version)
+		self.drain_storage_changes(backend, &mut cache, state_version)
 	}
 
 	/// Drain all changes into a [`StorageChanges`] instance. Leave empty overlay in place.
 	pub fn drain_storage_changes<B: Backend<H>, H: Hasher>(
 		&mut self,
 		backend: &B,
-		_parent_hash: H::Out,
 		mut cache: &mut StorageTransactionCache<B::Transaction, H>,
 		state_version: StateVersion,
 	) -> Result<StorageChanges<B::Transaction, H>, DefaultError>

substrate/primitives/state-machine/src/testing.rs

@@ -179,7 +179,6 @@ where
 	pub fn commit_all(&mut self) -> Result<(), String> {
 		let changes = self.overlay.drain_storage_changes::<_, _>(
 			&self.backend,
-			Default::default(),
 			&mut Default::default(),
 			self.state_version,
 		)?;