Add account preference controller.

- Add account preference controller and move the handling for
displaying user's accounts from AccountSettings to the
controller.

- Move AccountPreference and RemoveUserFragment from inner class to
standalone class.

- Add AccountRestrictionHelper to handle API that needs to be mocked for
testing.

Bug: 31801423
Test: make RunSettingsRoboTests
Change-Id: I3d16d0b6a8922a8abec7037c52b7a4de2d76eb0d

src/com/android/settings/accounts/RemoveUserFragment.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2016 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.accounts;
+
+import android.app.Dialog;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.os.Bundle;
+import android.os.UserManager;
+
+import com.android.internal.logging.nano.MetricsProto.MetricsEvent;
+import com.android.settings.core.instrumentation.InstrumentedDialogFragment;
+import com.android.settings.users.UserDialogs;
+
+class RemoveUserFragment extends InstrumentedDialogFragment {
+    private static final String ARG_USER_ID = "userId";
+
+    static RemoveUserFragment newInstance(int userId) {
+        Bundle args = new Bundle();
+        args.putInt(ARG_USER_ID, userId);
+        RemoveUserFragment fragment = new RemoveUserFragment();
+        fragment.setArguments(args);
+        return fragment;
+    }
+
+    @Override
+    public Dialog onCreateDialog(Bundle savedInstanceState) {
+        final int userId = getArguments().getInt(ARG_USER_ID);
+        return UserDialogs.createRemoveDialog(getActivity(), userId,
+            new DialogInterface.OnClickListener() {
+                @Override
+                public void onClick(DialogInterface dialog, int which) {
+                    UserManager um = (UserManager)
+                        getActivity().getSystemService(Context.USER_SERVICE);
+                    um.removeUser(userId);
+                }
+            });
+    }
+
+    @Override
+    public int getMetricsCategory() {
+        return MetricsEvent.DIALOG_REMOVE_USER;
+    }
+}