Add CDM dependency in Tethering

This change introduces a limited library for dependencies on
framework-connectivity from Tethering,
connectivity-internal-api-util, where all classes are annotated with
@RequiresApi(S) to ensure proper API checks are done before usage.

Bug: 245972418

Change-Id: I82bafd9063341adc71d07f0858e6d68283d081f0

framework/src/android/net/connectivity/TiramisuConnectivityInternalApiUtil.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2022 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 android.net.connectivity;
+
+import android.content.Context;
+import android.net.ConnectivityManager;
+import android.os.Build;
+import android.os.IBinder;
+
+import androidx.annotation.RequiresApi;
+
+/**
+ * Utility providing limited access to module-internal APIs which are only available on Android T+,
+ * as this class is only in the bootclasspath on T+ as part of framework-connectivity.
+ *
+ * R+ module components like Tethering cannot depend on all hidden symbols from
+ * framework-connectivity. They only have access to stable API stubs where newer APIs can be
+ * accessed after an API level check (enforced by the linter), or to limited hidden symbols in this
+ * class which is also annotated with @RequiresApi (so API level checks are also enforced by the
+ * linter).
+ * @hide
+ */
+@RequiresApi(Build.VERSION_CODES.TIRAMISU)
+public class TiramisuConnectivityInternalApiUtil {
+
+    /**
+     * Get a service binder token for
+     * {@link com.android.server.connectivity.wear.CompanionDeviceManagerProxyService}.
+     */
+    public static IBinder getCompanionDeviceManagerProxyService(Context ctx) {
+        final ConnectivityManager cm = ctx.getSystemService(ConnectivityManager.class);
+        return cm.getCompanionDeviceManagerProxyService();
+    }
+}