server+contractcourt: hand-off BreachCloseInfo to channel arbitrator

This also changes the chain_watcher and breacharbiter handoff. The
new logic ensures that the channel is only marked as pending closed
when the channel arbitrator has persisted the resolutions and commit
set.

contractcourt/chain_arbitrator.go

@@ -100,14 +100,12 @@ type ChainArbitratorConfig struct {
 	MarkLinkInactive func(wire.OutPoint) error
 
 	// ContractBreach is a function closure that the ChainArbitrator will
-	// use to notify the breachArbiter about a contract breach. A callback
-	// should be passed that when called will mark the channel pending
-	// close in the database. It should only return a non-nil error when the
-	// breachArbiter has preserved the necessary breach info for this
-	// channel point, and the callback has succeeded, meaning it is safe to
-	// stop watching the channel.
-	ContractBreach func(wire.OutPoint, *lnwallet.BreachRetribution,
-		func() error) error
+	// use to notify the breachArbiter about a contract breach. It should
+	// only return a non-nil error when the breachArbiter has preserved
+	// the necessary breach info for this channel point. Once the breach
+	// resolution is persisted in the channel arbitrator, it will be safe
+	// to mark the channel closed.
+	ContractBreach func(wire.OutPoint, *lnwallet.BreachRetribution) error
 
 	// IsOurAddress is a function that returns true if the passed address
 	// is known to the underlying wallet. Otherwise, false should be
@@ -512,19 +510,17 @@ func (c *ChainArbitrator) Start() error {
 
 		// First, we'll create an active chainWatcher for this channel
 		// to ensure that we detect any relevant on chain events.
+		breachClosure := func(ret *lnwallet.BreachRetribution) error {
+			return c.cfg.ContractBreach(chanPoint, ret)
+		}
+
 		chainWatcher, err := newChainWatcher(
 			chainWatcherConfig{
-				chanState: channel,
-				notifier:  c.cfg.Notifier,
-				signer:    c.cfg.Signer,
-				isOurAddr: c.cfg.IsOurAddress,
-				contractBreach: func(retInfo *lnwallet.BreachRetribution,
-					markClosed func() error) error {
-
-					return c.cfg.ContractBreach(
-						chanPoint, retInfo, markClosed,
-					)
-				},
+				chanState:           channel,
+				notifier:            c.cfg.Notifier,
+				signer:              c.cfg.Signer,
+				isOurAddr:           c.cfg.IsOurAddress,
+				contractBreach:      breachClosure,
 				extractStateNumHint: lnwallet.GetStateNumHint,
 			},
 		)
@@ -1122,11 +1118,11 @@ func (c *ChainArbitrator) WatchNewChannel(newChan *channeldb.OpenChannel) error
 			notifier:  c.cfg.Notifier,
 			signer:    c.cfg.Signer,
 			isOurAddr: c.cfg.IsOurAddress,
-			contractBreach: func(retInfo *lnwallet.BreachRetribution,
-				markClosed func() error) error {
+			contractBreach: func(
+				retInfo *lnwallet.BreachRetribution) error {
 
 				return c.cfg.ContractBreach(
-					chanPoint, retInfo, markClosed,
+					chanPoint, retInfo,
 				)
 			},
 			extractStateNumHint: lnwallet.GetStateNumHint,