Add summary provider for system tile.

Refactored getLocaleNames() into a FeatureProvider interface so it's
reusable and testable.

Bug: 31801428
Test: RunSettingsRoboTests
Change-Id: I2d31a66a4b32cfa7a364a4cfef1f6eea87084577

src/com/android/settings/localepicker/LocaleFeatureProvider.java

@@ -0,0 +1,25 @@
+/*
+ * 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.localepicker;
+
+public interface LocaleFeatureProvider {
+
+    /**
+     * Returns displayable string of device locales.
+     */
+    String getLocaleNames();
+}

src/com/android/settings/localepicker/LocaleFeatureProviderImpl.java

@@ -0,0 +1,36 @@
+/*
+ * 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.localepicker;
+
+import android.os.LocaleList;
+
+import com.android.internal.app.LocaleHelper;
+import com.android.internal.app.LocalePicker;
+
+import java.util.Locale;
+
+public class LocaleFeatureProviderImpl implements LocaleFeatureProvider {
+    @Override
+    public String getLocaleNames() {
+        final LocaleList locales = LocalePicker.getLocales();
+        final Locale displayLocale = Locale.getDefault();
+        return LocaleHelper.toSentenceCase(
+                LocaleHelper.getDisplayLocaleList(
+                        locales, displayLocale, 2 /* Show up to two locales from the list */),
+                displayLocale);
+    }
+}