Add WearDisplayService to the system server;
add a SET_DISPLAY_OFFSET permission.

Bug: 36515029
Test: No build failure; SystemServer loads as usual.
Change-Id: I253766553a507e2ada7d631501d8d32d863a823f
diff --git a/services/java/com/android/server/SystemServer.java b/services/java/com/android/server/SystemServer.java
index 4d5112f..0f4ad3e 100644
--- a/services/java/com/android/server/SystemServer.java
+++ b/services/java/com/android/server/SystemServer.java
@@ -186,6 +186,8 @@
             "com.google.android.clockwork.ThermalObserver";
     private static final String WEAR_CONNECTIVITY_SERVICE_CLASS =
             "com.google.android.clockwork.connectivity.WearConnectivityService";
+    private static final String WEAR_DISPLAY_SERVICE_CLASS =
+            "com.google.android.clockwork.display.WearDisplayService";
     private static final String WEAR_TIME_SERVICE_CLASS =
             "com.google.android.clockwork.time.WearTimeService";
     private static final String ACCOUNT_SERVICE_CLASS =
@@ -1506,6 +1508,7 @@
 
             if (!disableNonCoreServices) {
                 traceBeginAndSlog("StartWearTimeService");
+                mSystemServiceManager.startService(WEAR_DISPLAY_SERVICE_CLASS);
                 mSystemServiceManager.startService(WEAR_TIME_SERVICE_CLASS);
                 traceEnd();
             }