Create a launcher model override.

This change disables shortcuts/widgets loading on Android Go devices.
Bug: 112904271
Test: Manual test

Change-Id: I2c40f87a8f5d752525c99d254693a4e0a9eeeb2b

go/src/com/android/launcher3/model/WidgetsModel.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2018 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.launcher3.model;
+
+import android.content.Context;
+import android.os.UserHandle;
+
+import com.android.launcher3.icons.ComponentWithLabel;
+import com.android.launcher3.LauncherAppState;
+import com.android.launcher3.util.PackageUserKey;
+import com.android.launcher3.widget.WidgetListRowEntry;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+import androidx.annotation.Nullable;
+
+/**
+ * Widgets data model that is used by the adapters of the widget views and controllers.
+ *
+ * <p> The widgets and shortcuts are organized using package name as its index.
+ */
+public class WidgetsModel {
+    private static final ArrayList<WidgetListRowEntry> EMPTY_WIDGET_LIST = new ArrayList<>();
+
+    /**
+     * Returns a list of {@link WidgetListRowEntry}. All {@link WidgetItem} in a single row
+     * are sorted (based on label and user), but the overall list of {@link WidgetListRowEntry}s
+     * is not sorted. This list is sorted at the UI when using
+     * {@link com.android.launcher3.widget.WidgetsDiffReporter}
+     *
+     * @see com.android.launcher3.widget.WidgetsListAdapter#setWidgets(ArrayList)
+     */
+    public synchronized ArrayList<WidgetListRowEntry> getWidgetsList(Context context) {
+        return EMPTY_WIDGET_LIST;
+    }
+
+    /**
+     * @param packageUser If null, all widgets and shortcuts are updated and returned, otherwise
+     *                    only widgets and shortcuts associated with the package/user are.
+     */
+    public List<ComponentWithLabel> update(LauncherAppState app,
+            @Nullable PackageUserKey packageUser) {
+        return Collections.emptyList();
+    }
+
+
+    public void onPackageIconsUpdated(Set<String> packageNames, UserHandle user,
+            LauncherAppState app) {
+    }
+}