peer+contractcourt: delegate watching for co-op closes to the chainWatcher

In this commit, we modify the interaction between the chanCloser
sub-system and the chain notifier all together. This fixes a series of
bugs as before this commit, we wouldn’t be able to detect if the remote
party actually broadcasted *any* of the transactions that we signed off
upon. This would be rejected to the user by having a “zombie” channel
close that would never actually be resolved.

Rather than the chanCloser watching for on-chain closes, we’ll now open
up a co-op close context to the chainWatcher (via a layer of
indirection via the ChainArbitrator), and report to it all possible
closes that we’ve signed. The chainWatcher will then be able to launch
a goroutine to properly update the database state once any of the
possible closure transactions confirms.

peer_test.go

@@ -88,7 +88,7 @@ func TestPeerChannelClosureAcceptFeeResponder(t *testing.T) {
 	// We accept the fee, and send a ClosingSigned with the same fee back,
 	// so she knows we agreed.
 	peerFee := responderClosingSigned.FeeSatoshis
-	initiatorSig, err := initiatorChan.CreateCloseProposal(
+	initiatorSig, _, _, err := initiatorChan.CreateCloseProposal(
 		peerFee, dummyDeliveryScript, respDeliveryScript,
 	)
 	if err != nil {
@@ -178,7 +178,7 @@ func TestPeerChannelClosureAcceptFeeInitiator(t *testing.T) {
 		t.Fatalf("unable to query fee estimator: %v", err)
 	}
 	fee := btcutil.Amount(responderChan.CalcFee(uint64(feeRate * 1000)))
-	closeSig, err := responderChan.CreateCloseProposal(fee,
+	closeSig, _, _, err := responderChan.CreateCloseProposal(fee,
 		dummyDeliveryScript, initiatorDeliveryScript)
 	if err != nil {
 		t.Fatalf("unable to create close proposal: %v", err)
@@ -287,7 +287,7 @@ func TestPeerChannelClosureFeeNegotiationsResponder(t *testing.T) {
 	// We don't agree with the fee, and will send back one that's 2.5x.
 	preferredRespFee := responderClosingSigned.FeeSatoshis
 	increasedFee := btcutil.Amount(float64(preferredRespFee) * 2.5)
-	initiatorSig, err := initiatorChan.CreateCloseProposal(
+	initiatorSig, _, _, err := initiatorChan.CreateCloseProposal(
 		increasedFee, dummyDeliveryScript, respDeliveryScript,
 	)
 	if err != nil {
@@ -331,7 +331,7 @@ func TestPeerChannelClosureFeeNegotiationsResponder(t *testing.T) {
 
 	// We try negotiating a 2.1x fee, which should also be rejected.
 	increasedFee = btcutil.Amount(float64(preferredRespFee) * 2.1)
-	initiatorSig, err = initiatorChan.CreateCloseProposal(
+	initiatorSig, _, _, err = initiatorChan.CreateCloseProposal(
 		increasedFee, dummyDeliveryScript, respDeliveryScript,
 	)
 	if err != nil {
@@ -376,7 +376,7 @@ func TestPeerChannelClosureFeeNegotiationsResponder(t *testing.T) {
 
 	// Finally, we'll accept the fee by echoing back the same fee that they
 	// sent to us.
-	initiatorSig, err = initiatorChan.CreateCloseProposal(
+	initiatorSig, _, _, err = initiatorChan.CreateCloseProposal(
 		peerFee, dummyDeliveryScript, respDeliveryScript,
 	)
 	if err != nil {
@@ -471,7 +471,7 @@ func TestPeerChannelClosureFeeNegotiationsInitiator(t *testing.T) {
 		uint64(initiatorIdealFeeRate * 1000),
 	)
 	increasedFee := btcutil.Amount(float64(initiatorIdealFee) * 2.5)
-	closeSig, err := responderChan.CreateCloseProposal(
+	closeSig, _, _, err := responderChan.CreateCloseProposal(
 		increasedFee, dummyDeliveryScript, initiatorDeliveryScript,
 	)
 	if err != nil {
@@ -536,7 +536,7 @@ func TestPeerChannelClosureFeeNegotiationsInitiator(t *testing.T) {
 
 	// We try negotiating a 2.1x fee, which should also be rejected.
 	increasedFee = btcutil.Amount(float64(initiatorIdealFee) * 2.1)
-	responderSig, err := responderChan.CreateCloseProposal(
+	responderSig, _, _, err := responderChan.CreateCloseProposal(
 		increasedFee, dummyDeliveryScript, initiatorDeliveryScript,
 	)
 	if err != nil {
@@ -582,7 +582,7 @@ func TestPeerChannelClosureFeeNegotiationsInitiator(t *testing.T) {
 
 	// At this point, we'll accept their fee by sending back a CloseSigned
 	// message with an identical fee.
-	responderSig, err = responderChan.CreateCloseProposal(
+	responderSig, _, _, err = responderChan.CreateCloseProposal(
 		peerFee, dummyDeliveryScript, initiatorDeliveryScript,
 	)
 	if err != nil {