Showing recents in search

A list of recent queries will display when search first launches, or
when text query is empty.

Fix: 32452066
Test: make RunSettingsRoboTests
Change-Id: Ic697f8c0795f2315a01406537c7ce1bbf9a813be

tests/robotests/src/com/android/settings/testutils/DatabaseTestUtils.java

@@ -0,0 +1,36 @@
+/*
+ * 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.settings.testutils;
+
+import com.android.settings.search.IndexDatabaseHelper;
+
+import java.lang.reflect.Field;
+
+public class DatabaseTestUtils {
+
+    public static void clearDb() {
+        Field instance;
+        Class clazz = IndexDatabaseHelper.class;
+        try {
+            instance = clazz.getDeclaredField("sSingleton");
+            instance.setAccessible(true);
+            instance.set(null, null);
+        } catch (Exception e) {
+            throw new RuntimeException();
+        }
+    }
+}