Adding param comments and checking if registration status is valid.

Author: ankitaj224

firebase-installations/src/main/java/com/google/firebase/installations/FirebaseInstallations.java

@@ -218,10 +218,10 @@ private Void registerAndSaveFid(PersistedFidEntry persistedFidEntry)
 
       InstallationResponse installationResponse =
           serviceClient.createFirebaseInstallation(
-              firebaseApp.getOptions().getApiKey(),
-              persistedFidEntry.getFirebaseInstallationId(),
-              firebaseApp.getOptions().getProjectId(),
-              getApplicationId());
+              /*apiKey= */ firebaseApp.getOptions().getApiKey(),
+              /*fid= */ persistedFidEntry.getFirebaseInstallationId(),
+              /*projectID= */ firebaseApp.getOptions().getProjectId(),
+              /*appId= */ getApplicationId());
       persistedFid.insertOrUpdatePersistedFidEntry(
           PersistedFidEntry.builder()
               .setFirebaseInstallationId(persistedFidEntry.getFirebaseInstallationId())

firebase-installations/src/main/java/com/google/firebase/installations/local/PersistedFid.java

@@ -82,7 +82,9 @@ public synchronized PersistedFidEntry readPersistedFidEntryValue() {
         prefs.getLong(getSharedPreferencesKey(TOKEN_CREATION_TIME_IN_SECONDS_KEY), 0);
     long expiresIn = prefs.getLong(getSharedPreferencesKey(EXPIRES_IN_SECONDS_KEY), 0);
 
-    if (fid == null || status == -1) {
+    if (fid == null
+        || status == -1
+        || !(status >= 0 && status < RegistrationStatus.values().length)) {
       return null;
     }