Check for race condition between onAuthenticated and taskStackChanged

Bug: 111461540

Test: no more logs like the ones below

Change-Id: I784ecc71df1028bac8e0203156f79157f0509636
FingerprintService: onAuthenticated(owner=com.android.settings, id=-1049244503
FingerprintService: Stopping background authentication, top: com.example.android.biometric currentClient: com.android.settings
FingerprintService: client com.android.settings is no longer authenticating
FingerprintService: Done with client: com.android.settings
FingerprintService: handleError(client=null, error = 5)

services/core/java/com/android/server/biometrics/AuthenticationClient.java

@@ -232,6 +232,7 @@ public abstract class AuthenticationClient extends ClientMonitor {
     public boolean onAuthenticated(BiometricAuthenticator.Identifier identifier,
             boolean authenticated, ArrayList<Byte> token) {
         if (authenticated) {
+            mAlreadyDone = true;
             if (mRequireConfirmation) {
                 // Store the token so it can be sent to keystore after the user presses confirm
                 mEscrow = new TokenEscrow(identifier, token);

services/core/java/com/android/server/biometrics/BiometricServiceBase.java

@@ -408,7 +408,8 @@ public abstract class BiometricServiceBase extends SystemService
                         mActivityTaskManager.getTasks(1);
                 if (!runningTasks.isEmpty()) {
                     final String topPackage = runningTasks.get(0).topActivity.getPackageName();
-                    if (!topPackage.contentEquals(currentClient)) {
+                    if (!topPackage.contentEquals(currentClient)
+                            && !mCurrentClient.isAlreadyDone()) {
                         Slog.e(getTag(), "Stopping background authentication, top: " + topPackage
                                 + " currentClient: " + currentClient);
                         mCurrentClient.stop(false /* initiatedByClient */);

services/core/java/com/android/server/biometrics/ClientMonitor.java

@@ -63,6 +63,7 @@ public abstract class ClientMonitor implements IBinder.DeathRecipient {
     protected final Metrics mMetrics;
 
     protected boolean mAlreadyCancelled;
+    protected boolean mAlreadyDone;
 
     /**
      * @param context context of BiometricService
@@ -136,6 +137,11 @@ public abstract class ClientMonitor implements IBinder.DeathRecipient {
     public abstract boolean onEnumerationResult(
             BiometricAuthenticator.Identifier identifier, int remaining);
 
+
+    public boolean isAlreadyDone() {
+        return mAlreadyDone;
+    }
+
     /**
      * Called when we get notification from the biometric's HAL that an image has been acquired.
      * Common to authenticate and enroll.