Move service registration code into a System API (1/n)

This is an effort to modularize RollbackManager.

AIDL interfaces (IRollbackManager in this case) can’t be used across
module boundaries. We need to add a wrapper around the service
registraction code to expose to SystemServiceRegistry.

The approach is the same as ag/9746851.

Bug: 150347230
Test: m
Change-Id: I83e1cfedf4b4f6bf796e8a4a0ea81d813390f622
diff --git a/api/module-lib-current.txt b/api/module-lib-current.txt
index 69b52693..63159ed 100644
--- a/api/module-lib-current.txt
+++ b/api/module-lib-current.txt
@@ -9,6 +9,14 @@
 
 }
 
+package android.content.rollback {
+
+  public class RollbackManagerFrameworkInitializer {
+    method public static void initialize();
+  }
+
+}
+
 package android.net {
 
   public final class TetheredClient implements android.os.Parcelable {