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/offchain/primitives/Cargo.toml

@@ -7,12 +7,12 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"
 
 [dependencies]
-client = { package = "substrate-client", path = "../../client", default-features = false }
+sr-api = { path = "../../sr-api", default-features = false }
 sr-primitives = {  path = "../../sr-primitives", default-features = false }
 
 [features]
 default = ["std"]
 std = [
-	"client/std",
+	"sr-api/std",
 	"sr-primitives/std"
 ]

substrate/core/offchain/primitives/src/lib.rs

@@ -19,13 +19,12 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 #![warn(missing_docs)]
 
-use client::decl_runtime_apis;
 use sr_primitives::traits::NumberFor;
 
 /// Local Storage Prefix used by the Offchain Worker API to
 pub const STORAGE_PREFIX: &[u8] = b"storage";
 
-decl_runtime_apis! {
+sr_api::decl_runtime_apis! {
 	/// The offchain worker api.
 	pub trait OffchainWorkerApi {
 		/// Starts the off-chain task for given block number.