Add code inspector to ensure fragments implements search.

Unless a fragment is grandfathered:
- If it's a SearchPreferenceFragment, it needs to implement Indexable.
- If it's a Indexable, it needs to contain SEARCH_INDEX_DATA_PROVIDER.

Bug: 33209410
Test: make RunSettingsRoboTests
Change-Id: I078c54374341ba2966145429fc1507a3d5763d3b

tests/robotests/src/com/android/settings/SettingsRobolectricTestRunner.java

@@ -15,7 +15,6 @@
  */
 package com.android.settings;
 
-import java.util.List;
 import org.junit.runners.model.InitializationError;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.annotation.Config;
@@ -23,6 +22,8 @@ import org.robolectric.manifest.AndroidManifest;
 import org.robolectric.res.Fs;
 import org.robolectric.res.ResourcePath;
 
+import java.util.List;
+
 /**
  * Custom test runner for the testing of BluetoothPairingDialogs. This is needed because the
  * default behavior for robolectric is just to grab the resource directory in the target package.
@@ -47,7 +48,7 @@ public class SettingsRobolectricTestRunner extends RobolectricTestRunner {
         final String appRoot = "packages/apps/Settings";
         final String manifestPath = appRoot + "/AndroidManifest.xml";
         final String resDir = appRoot + "/res";
-        final String assetsDir = appRoot + "/assets";
+        final String assetsDir = appRoot + config.assetDir();
 
         // By adding any resources from libraries we need to the AndroidManifest, we can access
         // them from within the parallel universe's resource loader.