Add default implementation for several methods

Test: atest FingerprintServiceTest
Bug: 170518383

Change-Id: If724d26e85967a4b3ec07c22c706efca5cfc3f86
diff --git a/biometrics/fingerprint/aidl/default/Session.cpp b/biometrics/fingerprint/aidl/default/Session.cpp
index 372066d..96f1e56 100644
--- a/biometrics/fingerprint/aidl/default/Session.cpp
+++ b/biometrics/fingerprint/aidl/default/Session.cpp
@@ -55,15 +55,27 @@
 }
 
 ndk::ScopedAStatus Session::enumerateEnrollments(int32_t /*cookie*/) {
+    if (cb_) {
+        cb_->onStateChanged(0, SessionState::ENUMERATING_ENROLLMENTS);
+        cb_->onEnrollmentsEnumerated(std::vector<int32_t>());
+    }
     return ndk::ScopedAStatus::ok();
 }
 
 ndk::ScopedAStatus Session::removeEnrollments(int32_t /*cookie*/,
                                               const std::vector<int32_t>& /*enrollmentIds*/) {
+    if (cb_) {
+        cb_->onStateChanged(0, SessionState::REMOVING_ENROLLMENTS);
+        cb_->onEnrollmentsRemoved(std::vector<int32_t>());
+    }
     return ndk::ScopedAStatus::ok();
 }
 
 ndk::ScopedAStatus Session::getAuthenticatorId(int32_t /*cookie*/) {
+    if (cb_) {
+        cb_->onStateChanged(0, SessionState::GETTING_AUTHENTICATOR_ID);
+        cb_->onAuthenticatorIdRetrieved(0 /* authenticatorId */);
+    }
     return ndk::ScopedAStatus::ok();
 }