Add services-stubs for in-process APIs in services.jar

services-stubs is a stubs library for services.jar. It provides the
in-process APIs that's available inside the system server process
running services.jar.

Currently, all APIs in the jar are hidden by annotating
com.android.server package with @android.annotation.Hide. To add some
APIs,

1) remove package-info.java for com.android.server
2) add package-info.java for other sub packages
3) annotate them with @android.annotation.Hide except for the package
where the newly added APIs are in

This change also added android.annotation.Hide class which can be used
to hide an API without using the @hide javadoc tag. This opens up the
possibility of running metalava over the compiled jar, which is expected
to be much faster than when ran with source files.

Bug: 139391334
Test: m
Test: m services-stubs
Change-Id: I027b8a22b3e7533f6203aabb9dc3f690e4e842a6

services/Android.bp

@@ -14,6 +14,7 @@ filegroup {
         ":services.appwidget-sources",
         ":services.autofill-sources",
         ":services.backup-sources",
+        ":backuplib-sources",
         ":services.companion-sources",
         ":services.contentcapture-sources",
         ":services.contentsuggestions-sources",
@@ -101,3 +102,29 @@ filegroup {
     name: "art-profile",
     srcs: ["art-profile"],
 }
+
+// API stub
+// =============================================================
+
+droidstubs {
+    name: "services-stubs.sources",
+    srcs: [":services-sources"],
+    installable: false,
+    // TODO: remove the --hide options below
+    args: " --show-single-annotation android.annotation.SystemApi" +
+        " --hide-annotation android.annotation.Hide" +
+        " --hide-package com.google.android.startop.iorap" +
+        " --hide ReferencesHidden" +
+        " --hide DeprecationMismatch" +
+        " --hide HiddenTypedefConstant",
+    libs: [
+        "framework-all",
+    ],
+    visibility: ["//visibility:private"],
+}
+
+java_library {
+    name: "services-stubs",
+    srcs: [":services-stubs.sources"],
+    installable: false,
+}

services/core/java/com/android/server/package-info.java

@@ -0,0 +1,17 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+@android.annotation.Hide
+package com.android.server;

services/net/java/android/net/NetworkMonitorManager.java

@@ -16,6 +16,7 @@
 
 package android.net;
 
+import android.annotation.Hide;
 import android.annotation.NonNull;
 import android.os.Binder;
 import android.os.RemoteException;
@@ -33,6 +34,7 @@ import android.util.Log;
  * wrapper methods in this class return a boolean that callers can use to determine whether
  * RemoteException was thrown.
  */
+@Hide
 public class NetworkMonitorManager {
 
     @NonNull private final INetworkMonitor mNetworkMonitor;

services/net/java/android/net/ip/IpClientManager.java

@@ -16,6 +16,7 @@
 
 package android.net.ip;
 
+import android.annotation.Hide;
 import android.annotation.NonNull;
 import android.net.NattKeepalivePacketData;
 import android.net.ProxyInfo;
@@ -38,6 +39,7 @@ import android.util.Log;
  * wrapper methods in this class return a boolean that callers can use to determine whether
  * RemoteException was thrown.
  */
+@Hide
 public class IpClientManager {
     @NonNull private final IIpClient mIpClient;
     @NonNull private final String mTag;