Cleanup some obsolete TODOs and unused code.

Test: atest RollbackTest
Change-Id: I7b10533bb3658c113bfa9986b8241720b0a159a3
Merged-In: I67610d3467d737cbfc085f00ea0b509b63f4612b

services/core/java/com/android/server/rollback/RollbackManagerServiceImpl.java

@@ -157,9 +157,6 @@ class RollbackManagerServiceImpl extends IRollbackManager.Stub {
         mHandlerThread.start();
         Watchdog.getInstance().addThread(getHandler(), HANDLER_THREAD_TIMEOUT_DURATION_MILLIS);
 
-        // TODO: Make sure to register these call backs when a new user is
-        // added too.
-        SessionCallback sessionCallback = new SessionCallback();
         for (UserInfo userInfo : UserManager.get(mContext).getUsers(true)) {
             registerUserCallbacks(userInfo.getUserHandle());
         }
@@ -253,9 +250,6 @@ class RollbackManagerServiceImpl extends IRollbackManager.Stub {
             return;
         }
 
-        // TODO: Reuse the same SessionCallback and broadcast receiver
-        // instances, rather than creating new instances for each user.
-
         context.getPackageManager().getPackageInstaller()
                 .registerSessionCallback(new SessionCallback(), getHandler());