DO NOT MERGE API for reporting IMS registration failures

Draft API to report registration failures in the following
scenarios:
1. Idle mode failures - new IMS registration.
2. Ims registration handover failures - Handover of IMS registration
   from one access technology to another.

Bug: 33430556
Change-Id: Ie3bafec41c0198a66aa3ebca660a2a060e511c39

telephony/java/com/android/ims/internal/IImsRegistrationListener.aidl

@@ -107,4 +107,14 @@ interface IImsRegistrationListener {
      * Notifies the application when the list of URIs associated with IMS client is updated.
      */
     void registrationAssociatedUriChanged(in Uri[] uris);
+
+    /**
+     * Notifies the application when IMS registration attempt on a target
+     * access tech fails.
+     *
+     * @param targetAccessTech Radio access technology on which the IMS registration was
+     *         attempted.
+     * @param imsReasonInfo Reason for the failure.
+     */
+    void registrationChangeFailed(in int targetAccessTech, in ImsReasonInfo imsReasonInfo);
 }