Force loading of safe labels in system_server.

It's too easy for code to accidentally use loadLabel() when building
strings for security sensitive contexts, so add ability for a process
to always force loading of safe strings.

Test: builds, boots
Bug: 73657770
Change-Id: I1c7645bd7bebed0cfb6bc3e5bfd36c8cb11d4838

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

@@ -23,6 +23,7 @@ import android.content.ComponentName;
 import android.content.ContentResolver;
 import android.content.Context;
 import android.content.Intent;
+import android.content.pm.PackageItemInfo;
 import android.content.pm.PackageManager;
 import android.content.res.Configuration;
 import android.content.res.Resources.Theme;
@@ -331,6 +332,8 @@ public final class SystemServer {
 
             // The system server should never make non-oneway calls
             Binder.setWarnOnBlocking(true);
+            // The system server should always load safe labels
+            PackageItemInfo.setForceSafeLabels(true);
             // Deactivate SQLiteCompatibilityWalFlags until settings provider is initialized
             SQLiteCompatibilityWalFlags.init(null);