IMS: add an api to get IMS registration information.

Bug: 18668325
Change-Id: I240f5314b02edecf646dfa6f427138d9c8a22754
diff --git a/src/com/android/phone/PhoneInterfaceManager.java b/src/com/android/phone/PhoneInterfaceManager.java
index f44599d..1a5de74 100644
--- a/src/com/android/phone/PhoneInterfaceManager.java
+++ b/src/com/android/phone/PhoneInterfaceManager.java
@@ -2223,4 +2223,12 @@
                 && ImsManager.isEnhanced4gLteModeSettingEnabledByUser(mPhone.getContext())
                 && mTelephonySharedPreferences.getBoolean(PREF_ENABLE_VIDEO_CALLING, true);
     }
+
+    /*
+     * {@hide}
+     * Returns the IMS Registration Status
+     */
+    public boolean isImsRegistered() {
+        return mPhone.isImsRegistered();
+    }
 }