ota: rename observerKey to stateObserverKey

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@huawei.com>

ota/state_test.go

@@ -228,14 +228,14 @@ func (s *stateGuardSuite) TestAlterStateSuccess(c *C) {
 	c.Check(s.saved, DeepEquals, &ota.SystemState{BootMode: boot.Try})
 }
 
-type observerKey struct{}
+type stateObserverKey struct{}
 
 func (s *stateGuardSuite) TestObserver(c *C) {
-	s.guard.RegisterObserver(observerKey{}, func(st *ota.SystemState) error {
+	s.guard.RegisterObserver(stateObserverKey{}, func(st *ota.SystemState) error {
 		c.Assert(st.BootMode, Equals, boot.Try)
 		return nil
 	})
-	defer s.guard.RemoveObserver(observerKey{})
+	defer s.guard.RemoveObserver(stateObserverKey{})
 
 	err := s.guard.AlterState(func(st *ota.SystemState) (bool, error) {
 		st.BootMode = boot.Try
@@ -249,11 +249,11 @@ func (s *stateGuardSuite) TestObserver(c *C) {
 }
 
 func (s *stateGuardSuite) TestObserverError(c *C) {
-	s.guard.RegisterObserver(observerKey{}, func(st *ota.SystemState) error {
+	s.guard.RegisterObserver(stateObserverKey{}, func(st *ota.SystemState) error {
 		c.Assert(st.BootMode, Equals, boot.Try)
 		return errBoom
 	})
-	defer s.guard.RemoveObserver(observerKey{})
+	defer s.guard.RemoveObserver(stateObserverKey{})
 
 	err := s.guard.AlterState(func(st *ota.SystemState) (bool, error) {
 		st.BootMode = boot.Try