Allow SystemServer to create VCN service with a service initializer

We need to use "startService" to load the service via reflection
because the followup CLs will use a build system flag to control
whether the service is in Tethering module or the platform. Using
reflection ensures that in both case the system can build

Bug: 366598445
Test: atest FrameworksVcnTests && atest CtsVcnTestCases
Flag: EXEMPT no functional change
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:d6ecfc7de6ca836fa2eb92e05e5abbd3c7095cd7)

Change-Id: I165e83135c557619518257eb79a00b9ce5802c76
Merged-In: I165e83135c557619518257eb79a00b9ce5802c76
diff --git a/packages/Vcn/service-b/Android.bp b/packages/Vcn/service-b/Android.bp
index 26d8397..c1a1ee7 100644
--- a/packages/Vcn/service-b/Android.bp
+++ b/packages/Vcn/service-b/Android.bp
@@ -77,6 +77,7 @@
         "framework-connectivity-t-pre-jarjar",
         "framework-connectivity-b-pre-jarjar",
         "framework-wifi.stubs.module_lib",
+        "keepanno-annotations",
         "modules-utils-statemachine",
         "unsupportedappusage",
     ],
diff --git a/packages/Vcn/service-b/src/com/android/server/ConnectivityServiceInitializerB.java b/packages/Vcn/service-b/src/com/android/server/ConnectivityServiceInitializerB.java
new file mode 100644
index 0000000..02c8ce4
--- /dev/null
+++ b/packages/Vcn/service-b/src/com/android/server/ConnectivityServiceInitializerB.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server;
+
+import android.content.Context;
+import android.util.Log;
+
+import com.android.tools.r8.keepanno.annotations.KeepItemKind;
+import com.android.tools.r8.keepanno.annotations.UsedByReflection;
+
+/**
+ * Service initializer for VCN. This is called by system server to create a new instance of
+ * VcnManagementService.
+ */
+// This class is reflectively invoked from SystemServer and ConnectivityServiceInitializer.
+// Without this annotation, this class will be treated as unused class and be removed during build
+// time.
+@UsedByReflection(kind = KeepItemKind.CLASS_AND_METHODS)
+public final class ConnectivityServiceInitializerB extends SystemService {
+    private static final String TAG = ConnectivityServiceInitializerB.class.getSimpleName();
+    private final VcnManagementService mVcnManagementService;
+
+    public ConnectivityServiceInitializerB(Context context) {
+        super(context);
+        mVcnManagementService = VcnManagementService.create(context);
+    }
+
+    @Override
+    public void onStart() {
+        if (mVcnManagementService != null) {
+            Log.i(TAG, "Registering " + Context.VCN_MANAGEMENT_SERVICE);
+            publishBinderService(
+                    Context.VCN_MANAGEMENT_SERVICE,
+                    mVcnManagementService,
+                    /* allowIsolated= */ false);
+        }
+    }
+
+    @Override
+    public void onBootPhase(int phase) {
+        if (mVcnManagementService != null && phase == SystemService.PHASE_ACTIVITY_MANAGER_READY) {
+            Log.i(TAG, "Starting " + Context.VCN_MANAGEMENT_SERVICE);
+            mVcnManagementService.systemReady();
+        }
+    }
+}
diff --git a/services/Android.bp b/services/Android.bp
index 904becd..d99ed3d 100644
--- a/services/Android.bp
+++ b/services/Android.bp
@@ -254,10 +254,6 @@
         "service-permission.stubs.system_server",
         "service-rkp.stubs.system_server",
         "service-sdksandbox.stubs.system_server",
-
-        // TODO: b/30242953 This is for accessing IVcnManagementService and
-        // can be removed VCN is in mainline
-        "framework-connectivity-b-pre-jarjar",
     ],
 
     vintf_fragment_modules: [
diff --git a/services/java/com/android/server/SystemServer.java b/services/java/com/android/server/SystemServer.java
index 688312e..0718f04 100644
--- a/services/java/com/android/server/SystemServer.java
+++ b/services/java/com/android/server/SystemServer.java
@@ -411,6 +411,8 @@
             "/apex/com.android.tethering/javalib/service-connectivity.jar";
     private static final String CONNECTIVITY_SERVICE_INITIALIZER_CLASS =
             "com.android.server.ConnectivityServiceInitializer";
+    private static final String CONNECTIVITY_SERVICE_INITIALIZER_B_CLASS =
+            "com.android.server.ConnectivityServiceInitializerB";
     private static final String NETWORK_STATS_SERVICE_INITIALIZER_CLASS =
             "com.android.server.NetworkStatsServiceInitializer";
     private static final String UWB_APEX_SERVICE_JAR_PATH =
@@ -1447,7 +1449,6 @@
         IStorageManager storageManager = null;
         NetworkManagementService networkManagement = null;
         VpnManagerService vpnManager = null;
-        VcnManagementService vcnManagement = null;
         NetworkPolicyManagerService networkPolicy = null;
         WindowManagerService wm = null;
         NetworkTimeUpdateService networkTimeUpdater = null;
@@ -2145,8 +2146,10 @@
 
             t.traceBegin("StartVcnManagementService");
             try {
-                vcnManagement = VcnManagementService.create(context);
-                ServiceManager.addService(Context.VCN_MANAGEMENT_SERVICE, vcnManagement);
+                // TODO: b/375213246 When VCN is in mainline module, load it from the apex path.
+                // Whether VCN will be in apex or in the platform will be gated by a build system
+                // flag.
+                mSystemServiceManager.startService(CONNECTIVITY_SERVICE_INITIALIZER_B_CLASS);
             } catch (Throwable e) {
                 reportWtf("starting VCN Management Service", e);
             }
@@ -3038,7 +3041,6 @@
         final MediaRouterService mediaRouterF = mediaRouter;
         final MmsServiceBroker mmsServiceF = mmsService;
         final VpnManagerService vpnManagerF = vpnManager;
-        final VcnManagementService vcnManagementF = vcnManagement;
         final WindowManagerService windowManagerF = wm;
         final ConnectivityManager connectivityF = (ConnectivityManager)
                 context.getSystemService(Context.CONNECTIVITY_SERVICE);
@@ -3165,15 +3167,6 @@
                 reportWtf("making VpnManagerService ready", e);
             }
             t.traceEnd();
-            t.traceBegin("MakeVcnManagementServiceReady");
-            try {
-                if (vcnManagementF != null) {
-                    vcnManagementF.systemReady();
-                }
-            } catch (Throwable e) {
-                reportWtf("making VcnManagementService ready", e);
-            }
-            t.traceEnd();
             t.traceBegin("MakeNetworkPolicyServiceReady");
             try {
                 if (networkPolicyF != null) {