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/AccountRestrictionHelper.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.annotation.UserIdInt;
+import android.content.Context;
+import com.android.settings.AccessiblePreferenceCategory;
+import com.android.settingslib.RestrictedLockUtils;
+import com.android.settingslib.RestrictedPreference;
+
+public class AccountRestrictionHelper {
+
+    private final Context mContext;
+
+    public AccountRestrictionHelper(Context context) {
+        mContext = context;
+    }
+
+    /**
+     * Configure the UI of the preference by checking user restriction.
+     * @param preference The preference we are configuring.
+     * @param userRestriction The user restriction related to the preference.
+     * @param userId The user that we retrieve user restriction of.
+     */
+    public void enforceRestrictionOnPreference(RestrictedPreference preference,
+        String userRestriction, @UserIdInt int userId) {
+        if (preference == null) {
+            return;
+        }
+        if (hasBaseUserRestriction(userRestriction, userId)) {
+            preference.setEnabled(false);
+        } else {
+            preference.checkRestrictionAndSetDisabled(userRestriction, userId);
+        }
+    }
+
+    public boolean hasBaseUserRestriction(String userRestriction, @UserIdInt int userId) {
+        return RestrictedLockUtils.hasBaseUserRestriction(mContext, userRestriction, userId);
+    }
+
+    public AccessiblePreferenceCategory createAccessiblePreferenceCategory(Context context) {
+        return new AccessiblePreferenceCategory(context);
+    }
+
+}