Cherry pick Make WebViewUpdateService a SystemService. DO NOT MERGE

Migrate WebViewUpdateService to the newer SystemService approach instead
of ServiceManager.addService.

Original Bug: 16403706
Original Change-Id: I21aa67a41c22c3c20ba9e82eb87e5d610fe130e8

Bug: 16723226
Change-Id: Id276b71ee547e683f0756bcee0f4978ce342c2af
diff --git a/services/java/com/android/server/SystemServer.java b/services/java/com/android/server/SystemServer.java
index 6f185d5..e8d6773 100644
--- a/services/java/com/android/server/SystemServer.java
+++ b/services/java/com/android/server/SystemServer.java
@@ -376,6 +376,9 @@
         mSystemServiceManager.startService(UsageStatsService.class);
         mActivityManagerService.setUsageStatsManager(
                 LocalServices.getService(UsageStatsManagerInternal.class));
+
+        // Tracks whether the updatable WebView is in a ready state and watches for update installs.
+        mSystemServiceManager.startService(WebViewUpdateService.class);
     }
 
     /**
@@ -422,9 +425,6 @@
             Slog.i(TAG, "Reading configuration...");
             SystemConfig.getInstance();
 
-            Slog.i(TAG, "WebView Update Service");
-            ServiceManager.addService("webviewupdate", new WebViewUpdateService(context));
-
             Slog.i(TAG, "Scheduling Policy");
             ServiceManager.addService("scheduling_policy", new SchedulingPolicyService());