accounts: use time.Duration correctly

There is no point to using time.Duration if the value is interpreted as
milliseconds. Callers should use the standard multiplication idiom to
choose the unit. In fact, the only caller outside of the tests already
does so.

accounts/account_manager.go

@@ -33,6 +33,7 @@ and accounts persistence is derived from stored keys' addresses
 package accounts
 
 import (
+	"crypto/ecdsa"
 	crand "crypto/rand"
 
 	"errors"
@@ -52,17 +53,17 @@ type Account struct {
 }
 
 type AccountManager struct {
-	keyStore           crypto.KeyStore2
-	unlockedKeys       map[string]crypto.Key
-	unlockMilliseconds time.Duration
-	mutex              sync.RWMutex
+	keyStore     crypto.KeyStore2
+	unlockedKeys map[string]crypto.Key
+	unlockTime   time.Duration
+	mutex        sync.RWMutex
 }
 
-func NewAccountManager(keyStore crypto.KeyStore2, unlockMilliseconds time.Duration) *AccountManager {
+func NewAccountManager(keyStore crypto.KeyStore2, unlockTime time.Duration) *AccountManager {
 	return &AccountManager{
-		keyStore:           keyStore,
-		unlockedKeys:       make(map[string]crypto.Key),
-		unlockMilliseconds: unlockMilliseconds,
+		keyStore:     keyStore,
+		unlockedKeys: make(map[string]crypto.Key),
+		unlockTime:   unlockTime,
 	}
 }
 
@@ -144,7 +145,7 @@ func (am *AccountManager) Accounts() ([]Account, error) {
 
 func unlockLater(am *AccountManager, addr []byte) {
 	select {
-	case <-time.After(time.Millisecond * am.unlockMilliseconds):
+	case <-time.After(am.unlockTime):
 	}
 	am.mutex.RLock()
 	// TODO: how do we know the key is actually gone from memory?