Call ActivityManagerService.enterSafeMode

This fixes the accidental removal (change ID
If2e6afe21f6efcb141f3a4428ff9154b68f08a1d)
of a call to ActivityManagerService.enterSafeMode, ensuring that
when the rest of the device is in safe mode, ActivityManagerService
and PackageManagerService are made aware of it and properly filter
app launches.

Fixes: 137052912
Test: manual; safe mode correctly blocks 3p apps
Change-Id: Ie2caf6d2fd74b241927a245393fb31658201962f
Merged-In: Ie2caf6d2fd74b241927a245393fb31658201962f

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

@@ -1671,6 +1671,10 @@ public final class SystemServer {
         mSystemServiceManager.startService(StatsCompanionService.Lifecycle.class);
         traceEnd();
 
+        if (safeMode) {
+            mActivityManagerService.enterSafeMode();
+        }
+
         // MMS service broker
         traceBeginAndSlog("StartMmsService");
         mmsService = mSystemServiceManager.startService(MmsServiceBroker.class);