Refactor sr-api to not depend on client anymore (#4086)

* Refactor sr-api to not depend on client anymore

* Fix benches

* Apply suggestions from code review

Co-Authored-By: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* Apply suggestions from code review

substrate/core/transaction-pool/runtime-api/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "substrate-transaction-pool-runtime-api"
+version = "2.0.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
+
+[dependencies]
+sr-primitives = { path = "../../sr-primitives", default-features = false }
+primitives = { package = "substrate-primitives",  path = "../../primitives", default-features = false }
+sr-api = { path = "../../sr-api", default-features = false }
+
+[features]
+default = [ "std" ]
+std = [ "sr-primitives/std", "primitives/std", "sr-api/std" ]

substrate/core/transaction-pool/runtime-api/src/lib.rs

@@ -0,0 +1,29 @@
+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Substrate runtime api for the transaction queue.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+use sr_primitives::{transaction_validity::TransactionValidity, traits::Block as BlockT};
+
+sr_api::decl_runtime_apis! {
+	/// The `TaggedTransactionQueue` api trait for interfering with the transaction queue.
+	pub trait TaggedTransactionQueue {
+		/// Validate the given transaction.
+		fn validate_transaction(tx: <Block as BlockT>::Extrinsic) -> TransactionValidity;
+	}
+}