Index Data to build Slices in Settings

The indexing is done by taking the indexable fragments from
search, grabbing their XML via SearchIndexableResources, and
then looking for controllers defined in preferences.

For each controller found, we take the combination of the
fragment providing the XML and the Preference info to create
an indexable row.

Buiding a Slice will be handled in a subsquent CL, but a
prototype can be found here: ag/3324435

Test: robotests
Bug: 67996923
Change-Id: I48668618079bcc3da55ab77b7323ee8e467073af

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

@@ -19,12 +19,33 @@ package com.android.settings.testutils;
 import android.content.Context;
 
 import com.android.settings.search.IndexDatabaseHelper;
+import com.android.settings.slices.SlicesDatabaseHelper;
 
 import java.lang.reflect.Field;
 
 public class DatabaseTestUtils {
 
     public static void clearDb(Context context) {
+        clearSearchDb(context);
+        clearSlicesDb(context);
+    }
+
+    private static void clearSlicesDb(Context context) {
+        SlicesDatabaseHelper helper = SlicesDatabaseHelper.getInstance(context);
+        helper.close();
+
+        Field instance;
+        Class clazz = SlicesDatabaseHelper.class;
+        try {
+            instance = clazz.getDeclaredField("sSingleton");
+            instance.setAccessible(true);
+            instance.set(null, null);
+        } catch (Exception e) {
+            throw new RuntimeException();
+        }
+    }
+
+    private static void clearSearchDb(Context context) {
         IndexDatabaseHelper helper = IndexDatabaseHelper.getInstance(context);
         helper.close();