Ensure trust agents are only provided by platform packages

Ensures that Settings only shows TrustAgentServices from
platform packages.

Bug: 15287044
Change-Id: I62c131d99c7266f8617ec32a50a4f5549a07b4b7

src/com/android/settings/AdvancedSecuritySettings.java

@@ -109,6 +109,7 @@ public class AdvancedSecuritySettings extends ListFragment implements View.OnCli
 
         for (ResolveInfo resolveInfo : resolveInfos) {
             if (resolveInfo.serviceInfo == null) continue;
+            if (!TrustAgentUtils.checkProvidePermission(resolveInfo, pm)) continue;
             ComponentName name = TrustAgentUtils.getComponentName(resolveInfo);
             if (!mAvailableAgents.containsKey(name)) {
                 AgentInfo agentInfo = new AgentInfo();