Removed screen on/off callbacks from NPMS.

NetworkPolicyManagerService (NPMS) used to depend on screen on/off
changes to determine if a foreground activity should have network
restrictions, but such check is now redundant since ActivityManager
already changes the proper UID state (like going from TOP to
TOP_SLEEPING) when the screen status is changed.

Removing such code decreases the NPMS lock contention when the screen is
turned on in about 3-5ms.

Change-Id: I2853443efedbf14961ae9a5b2e72689d4d1a646c
BUG: 30785671
(cherry picked from commit 88f40ad9a7)

services/java/com/android/server/SystemServer.java

@@ -809,10 +809,8 @@ public final class SystemServer {
 
                 traceBeginAndSlog("StartNetworkPolicyManagerService");
                 try {
-                    networkPolicy = new NetworkPolicyManagerService(
-                            context, mActivityManagerService,
-                            (IPowerManager)ServiceManager.getService(Context.POWER_SERVICE),
-                            networkStats, networkManagement);
+                    networkPolicy = new NetworkPolicyManagerService(context,
+                            mActivityManagerService, networkStats, networkManagement);
                     ServiceManager.addService(Context.NETWORK_POLICY_SERVICE, networkPolicy);
                 } catch (Throwable e) {
                     reportWtf("starting NetworkPolicy Service", e);