Add a constant to allow system-provided fingerprint dialogs

This adds FINGERPRINT_ERROR_USER_CANCELED to the list of possible errors
returned by FingerprintManager.authenticate().

Fixes b/64540509

Test: documentation builds

Change-Id: I66b46d385ab10eb0bc8e982c06e7a60570a79165

core/java/android/hardware/fingerprint/FingerprintManager.java

@@ -127,6 +127,13 @@ public class FingerprintManager {
      */
     public static final int FINGERPRINT_ERROR_LOCKOUT_PERMANENT = 9;
 
+    /**
+     * The user canceled the operation. Upon receiving this, applications should use alternate
+     * authentication (e.g. a password). The application should also provide the means to return
+     * to fingerprint authentication, such as a "use fingerprint" button.
+     */
+    public static final int FINGERPRINT_ERROR_USER_CANCELED = 10;
+
     /**
      * @hide
      */