Add ability to show/hide accessibility_shortcut_preference.

This adds a new boolean flag,
config_show_accessibility_shortcut_preference, which when set to false
will hide the accessibility shortcut preference item.

Bug: 62387367
Test: make RunSettingsRoboTests
ROBOTEST_FILTER=AccessibilitySettingsTest
Change-Id: I3fd941695df1ad89f717f464d2383be909839a3b

tests/robotests/src/com/android/internal/accessibility/AccessibilityShortcutController.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2017 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.internal.accessibility;
+
+import android.content.ComponentName;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Fake controller to make robolectric test compile. Should be removed when Robolectric supports
+ * API 25.
+ */
+public class AccessibilityShortcutController {
+
+    public static Map<ComponentName, AccessibilityShortcutController.ToggleableFrameworkFeatureInfo>
+        getFrameworkShortcutFeaturesMap() {
+        return new HashMap<>();
+    }
+
+    public static class ToggleableFrameworkFeatureInfo {
+        private String mSettingKey;
+
+        public String getSettingKey() {
+            return mSettingKey;
+        }
+    }
+}