Add ChainTime associated type (#410)

* add HeaderTimestamp associated type

* use Header Timestamp

* rename HeaderTimestamp to ChainTime

* add unit test

* deal with clippy

* Apply suggestions from code review

Commit review suggestions

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

* code review

* cargo fmt

* get rid of additional test runtime

* unit test asserts against concrete import context

Co-authored-by: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

bridges/bin/rialto/runtime/src/kovan.rs

@@ -21,7 +21,8 @@ use bp_header_chain::BaseHeaderChain;
 use frame_support::RuntimeDebug;
 use hex_literal::hex;
 use pallet_bridge_eth_poa::{
-	AuraConfiguration, PruningStrategy as BridgePruningStrategy, ValidatorsConfiguration, ValidatorsSource,
+	AuraConfiguration, ChainTime as TChainTime, PruningStrategy as BridgePruningStrategy, ValidatorsConfiguration,
+	ValidatorsSource,
 };
 use sp_std::prelude::*;
 
@@ -134,6 +135,17 @@ impl BridgePruningStrategy for PruningStrategy {
 	}
 }
 
+/// PoA Header timestamp verification against `Timestamp` pallet.
+#[derive(Default, RuntimeDebug)]
+pub struct ChainTime;
+
+impl TChainTime for ChainTime {
+	fn is_timestamp_ahead(&self, timestamp: u64) -> bool {
+		let now = super::Timestamp::now();
+		timestamp > now
+	}
+}
+
 /// The Kovan Blockchain as seen by the runtime.
 pub struct KovanBlockchain;