Add API surface for "keep SMS app running".

Bug: 109809543
Test: build & boot
Change-Id: Ie9ebf1f34052394a92c3f260413c18596709d3a3
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index 5a1f2e8..ade0b11 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -4144,6 +4144,10 @@
     <permission android:name="android.permission.MONITOR_DEFAULT_SMS_PACKAGE"
         android:protectionLevel="signature" />
 
+    <!-- A subclass of {@link android.app.SmsAppService} must be protected with this permission. -->
+    <permission android:name="android.permission.BIND_SMS_APP_SERVICE"
+        android:protectionLevel="signature" />
+
     <application android:process="system"
                  android:persistent="true"
                  android:hasCode="false"