Add VPN settings classes to Settings app.

PATCH SET 2:
+ Add import com.android.settings.R

PATCH SET 3:
+ Remove @Override interface methods to be compilable by Java 1.5.

PATCH SET 4:
+ Add import android.net.vpn.VpnManager

PATCH SET 5:
+ Add license headers.

PATCH SET 6:
+ Remove Constant.java and move the constants to VpnSettings.
+ Make AuthenticationActor implement DialogInterface's handlers.
+ Remove trailing spaces.

PATCH SET 7:
+ Remove default username.

src/com/android/settings/vpn/VpnProfileActor.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2007 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.settings.vpn;
+
+import android.net.vpn.VpnProfile;
+import android.os.Bundle;
+
+/**
+ * The interface to act on a {@link VpnProfile}.
+ */
+public interface VpnProfileActor {
+    VpnProfile getProfile();
+
+    /**
+     * Establishes a VPN connection.
+     */
+    void connect();
+
+    /**
+     * Tears down the connection.
+     */
+    void disconnect();
+
+    /**
+     * Checks the current status. The result is expected to be broadcast.
+     * Use {@link VpnManager#registerConnectivityReceiver()} to register a
+     * broadcast receiver and to receives the broadcast events.
+     */
+    void checkStatus();
+
+    /**
+     * Called to save the states when the device is rotated.
+     */
+    void onSaveState(Bundle outState);
+
+    /**
+     * Called to restore the states on the rotated screen.
+     */
+    void onRestoreState(Bundle savedState);
+}