Add L2TP secret, L2TP/IPSec PSK support. Fix screen orientation.

* Changes
  + Add L2tpActor, L2tpEditor, L2tpIpsecPskActor.
  + Make L2tpIpsecEditor extend L2tpEditor.
  + Revise the code for saving username. Make
    VpnSettings.saveProfileToStorage() static.
  + Fix support for screen orientation change in both VpnSettings and
    VpnEditor.

  Patch Set 2:
  + Remove Util.isNullOrEmpty(). Use TextUtils.isEmpty() instead.
  + Remove unused imports. Wrap lines longer than 80 chars.

  Patch Set 3:
  + Fix all the strings according to UI feedback.
  + Remove all the added actor subclasses and move password to editor.
  + Remove VPN entry in Security & location.

  Patch Set 4:
  + Misc string fixes.

  Patch Set 5:
  + Add strings for credential storage settings.
  + Changed the error dialog icon.
  + Fix "Remember me" indentation in connect dialog.

  Patch Set 6:
  + resolve res/values/strings.xml

src/com/android/settings/vpn/L2tpIpsecEditor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2007 The Android Open Source Project
+ * Copyright (C) 2009 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.
@@ -25,11 +25,12 @@ import android.preference.ListPreference;
 import android.preference.Preference;
 import android.preference.PreferenceGroup;
 import android.security.Keystore;
+import android.text.TextUtils;
 
 /**
  * The class for editing {@link L2tpIpsecProfile}.
  */
-class L2tpIpsecEditor extends VpnProfileEditor {
+class L2tpIpsecEditor extends L2tpEditor {
     private static final String TAG = L2tpIpsecEditor.class.getSimpleName();
 
     private ListPreference mUserCertificate;
@@ -44,23 +45,22 @@ class L2tpIpsecEditor extends VpnProfileEditor {
 
     @Override
     protected void loadExtraPreferencesTo(PreferenceGroup subpanel) {
+        super.loadExtraPreferencesTo(subpanel);
         Context c = subpanel.getContext();
         subpanel.addPreference(createUserCertificatePreference(c));
         subpanel.addPreference(createCaCertificatePreference(c));
     }
 
     @Override
-    public String validate(Context c) {
-        String result = super.validate(c);
-        if (result != null) {
-            return result;
-        } 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;
+    public String validate() {
+        String result = super.validate();
+        if (result == null) {
+            result = validate(mUserCertificate, R.string.vpn_user_certificate);
         }
+        if (result == null) {
+            result = validate(mCaCertificate, R.string.vpn_ca_certificate);
+        }
+        return result;
     }
 
     private Preference createUserCertificatePreference(Context c) {
@@ -72,9 +72,13 @@ class L2tpIpsecEditor extends VpnProfileEditor {
                     public boolean onPreferenceChange(
                             Preference pref, Object newValue) {
                         mProfile.setUserCertificate((String) newValue);
-                        return onPreferenceChangeCommon(pref, newValue);
+                        setSummary(pref, R.string.vpn_user_certificate,
+                                (String) newValue);
+                        return true;
                     }
                 });
+        setSummary(mUserCertificate, R.string.vpn_user_certificate,
+                mProfile.getUserCertificate());
         return mUserCertificate;
     }
 
@@ -87,9 +91,13 @@ class L2tpIpsecEditor extends VpnProfileEditor {
                     public boolean onPreferenceChange(
                             Preference pref, Object newValue) {
                         mProfile.setCaCertificate((String) newValue);
-                        return onPreferenceChangeCommon(pref, newValue);
+                        setSummary(pref, R.string.vpn_ca_certificate,
+                                (String) newValue);
+                        return true;
                     }
                 });
+        setSummary(mCaCertificate, R.string.vpn_ca_certificate,
+                mProfile.getCaCertificate());
         return mCaCertificate;
     }
 
@@ -103,13 +111,7 @@ class L2tpIpsecEditor extends VpnProfileEditor {
         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;
-    }
 }