Fix API change

Author: tejasd

firebase-perf/api.txt

@@ -3,7 +3,6 @@ package com.google.firebase.perf {
 
   @javax.inject.Singleton public class FirebasePerformance {
     method public static com.google.firebase.perf.FirebasePerformance getInstance();
-    method @VisibleForTesting protected com.google.firebase.sessions.api.SessionSubscriber getSessionSubscriber();
     method public boolean isPerformanceCollectionEnabled();
     method public com.google.firebase.perf.metrics.HttpMetric newHttpMetric(String, @com.google.firebase.perf.FirebasePerformance.HttpMethod String);
     method public com.google.firebase.perf.metrics.HttpMetric newHttpMetric(java.net.URL, @com.google.firebase.perf.FirebasePerformance.HttpMethod String);

firebase-perf/src/main/java/com/google/firebase/perf/FirebasePerformance.java

@@ -468,7 +468,7 @@ Boolean getPerformanceCollectionForceEnabledState() {
 
   @NonNull
   @VisibleForTesting
-  protected SessionSubscriber getSessionSubscriber() {
+  SessionSubscriber getSessionSubscriber() {
     return sessionSubscriber;
   }
 }