Addressing Rayo's comments.

Author: ankitaj224

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

@@ -231,7 +231,7 @@ public Task<String> getId() {
     }
 
     Task<String> task = addGetIdListener();
-    backgroundExecutor.execute(this::doGetId);
+    backgroundExecutor.execute(() -> doRegistrationInternal(false));
     return task;
   }
 
@@ -248,11 +248,7 @@ public Task<String> getId() {
   public Task<InstallationTokenResult> getToken(boolean forceRefresh) {
     preConditionChecks();
     Task<InstallationTokenResult> task = addGetAuthTokenListener();
-    if (forceRefresh) {
-      backgroundExecutor.execute(this::doGetAuthTokenForceRefresh);
-    } else {
-      backgroundExecutor.execute(this::doGetAuthTokenWithoutForceRefresh);
-    }
+    backgroundExecutor.execute(() -> doRegistrationInternal(forceRefresh));
     return task;
   }
 
@@ -270,20 +266,22 @@ public Task<Void> delete() {
   private Task<String> addGetIdListener() {
     TaskCompletionSource<String> taskCompletionSource = new TaskCompletionSource<>();
     StateListener l = new GetIdListener(taskCompletionSource);
-    synchronized (lock) {
-      listeners.add(l);
-    }
+    addStateListeners(l);
     return taskCompletionSource.getTask();
   }
 
   private Task<InstallationTokenResult> addGetAuthTokenListener() {
     TaskCompletionSource<InstallationTokenResult> taskCompletionSource =
         new TaskCompletionSource<>();
     StateListener l = new GetAuthTokenListener(utils, taskCompletionSource);
+    addStateListeners(l);
+    return taskCompletionSource.getTask();
+  }
+
+  private void addStateListeners(StateListener l) {
     synchronized (lock) {
       listeners.add(l);
     }
-    return taskCompletionSource.getTask();
   }
 
   private void triggerOnStateReached(PersistedInstallationEntry persistedInstallationEntry) {
@@ -320,18 +318,6 @@ private synchronized String getCacheFid() {
     return cachedFid;
   }
 
-  private final void doGetAuthTokenForceRefresh() {
-    doRegistrationInternal(true);
-  }
-
-  private final void doGetAuthTokenWithoutForceRefresh() {
-    doRegistrationInternal(false);
-  }
-
-  private final void doGetId() {
-    doRegistrationInternal(false);
-  }
-
   /**
    * Logic for handling get id and the two forms of get auth token. This handles all the work,
    * including creating a new FID if one hasn't been generated yet and making the network calls to

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

@@ -17,6 +17,10 @@
 import com.google.android.gms.tasks.TaskCompletionSource;
 import com.google.firebase.installations.local.PersistedInstallationEntry;
 
+/**
+ * This class manages {@link PersistedInstallationEntry} state transitions valid for getId() and
+ * updates the caller once the id is generated.
+ */
 class GetIdListener implements StateListener {
   final TaskCompletionSource<String> taskCompletionSource;
 
@@ -32,6 +36,8 @@ public boolean onStateReached(PersistedInstallationEntry persistedInstallationEn
       taskCompletionSource.trySetResult(persistedInstallationEntry.getFirebaseInstallationId());
       return true;
     }
+    // Don't update the caller if the PersistedInstallationEntry registration status is
+    // ATTEMPT_MIGRATION or NOT_GENERATED.
     return false;
   }