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/L2tpIpsecEditor.java

@@ -0,0 +1,138 @@
+/*
+ * 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 com.android.settings.R;
+
+import android.content.Context;
+import android.net.vpn.L2tpIpsecProfile;
+import android.preference.EditTextPreference;
+import android.preference.ListPreference;
+import android.preference.Preference;
+import android.preference.PreferenceGroup;
+import android.security.Keystore;
+
+/**
+ * The class for editing {@link L2tpIpsecProfile}.
+ */
+class L2tpIpsecEditor extends SingleServerEditor {
+    private static final String TAG = L2tpIpsecEditor.class.getSimpleName();
+
+    private ListPreference mUserCertificate;
+    private ListPreference mCaCertificate;
+    private ListPreference mUserkey;
+
+    private L2tpIpsecProfile mProfile;
+
+    public L2tpIpsecEditor(L2tpIpsecProfile p) {
+        super(p);
+        mProfile = p;
+    }
+
+    //@Override
+    public void loadPreferencesTo(PreferenceGroup subsettings) {
+        super.loadPreferencesTo(subsettings);
+        Context c = subsettings.getContext();
+        subsettings.addPreference(createUserkeyPreference(c));
+        subsettings.addPreference(createUserCertificatePreference(c));
+        subsettings.addPreference(createCaCertificatePreference(c));
+        subsettings.addPreference(createDomainSufficesPreference(c));
+    }
+
+    //@Override
+    public String validate(Context c) {
+        String result = super.validate(c);
+        if (result != null) {
+            return result;
+        } else if (mProfile.isCustomized()) {
+            return null;
+        } else if (Util.isNullOrEmpty(mUserkey.getValue())) {
+            return c.getString(R.string.vpn_error_userkey_not_selected);
+        } else if (Util.isNullOrEmpty(mUserCertificate.getValue())) {
+            return c.getString(R.string.vpn_error_user_certificate_not_selected);
+        } else if (Util.isNullOrEmpty(mCaCertificate.getValue())) {
+            return c.getString(R.string.vpn_error_ca_certificate_not_selected);
+        } else {
+            return null;
+        }
+    }
+
+    private Preference createUserCertificatePreference(Context c) {
+        mUserCertificate = createListPreference(c,
+                R.string.vpn_user_certificate_title,
+                mProfile.getUserCertificate(),
+                Keystore.getInstance().getAllCertificateKeys(),
+                new Preference.OnPreferenceChangeListener() {
+                    public boolean onPreferenceChange(
+                            Preference pref, Object newValue) {
+                        mProfile.setUserCertificate((String) newValue);
+                        return onPreferenceChangeCommon(pref, newValue);
+                    }
+                });
+        return mUserCertificate;
+    }
+
+    private Preference createCaCertificatePreference(Context c) {
+        mCaCertificate = createListPreference(c,
+                R.string.vpn_ca_certificate_title,
+                mProfile.getCaCertificate(),
+                Keystore.getInstance().getAllCertificateKeys(),
+                new Preference.OnPreferenceChangeListener() {
+                    public boolean onPreferenceChange(
+                            Preference pref, Object newValue) {
+                        mProfile.setCaCertificate((String) newValue);
+                        return onPreferenceChangeCommon(pref, newValue);
+                    }
+                });
+        return mCaCertificate;
+    }
+
+    private Preference createUserkeyPreference(Context c) {
+        mUserkey = createListPreference(c,
+                R.string.vpn_userkey_title,
+                mProfile.getUserkey(),
+                Keystore.getInstance().getAllUserkeyKeys(),
+                new Preference.OnPreferenceChangeListener() {
+                    public boolean onPreferenceChange(
+                            Preference pref, Object newValue) {
+                        mProfile.setUserkey((String) newValue);
+                        return onPreferenceChangeCommon(pref, newValue);
+                    }
+                });
+        return mUserkey;
+    }
+
+    private ListPreference createListPreference(Context c, int titleResId,
+            String text, String[] keys,
+            Preference.OnPreferenceChangeListener listener) {
+        ListPreference pref = new ListPreference(c);
+        pref.setTitle(titleResId);
+        pref.setDialogTitle(titleResId);
+        pref.setPersistent(true);
+        pref.setEntries(keys);
+        pref.setEntryValues(keys);
+        pref.setValue(text);
+        pref.setSummary(checkNull(text, c));
+        pref.setOnPreferenceChangeListener(listener);
+        return pref;
+    }
+
+    private boolean onPreferenceChangeCommon(Preference pref, Object newValue) {
+        pref.setSummary(checkNull(newValue.toString(), pref.getContext()));
+        return true;
+    }
+}