Enable highlighting of Print services

- add to SettingsPreferenceFragment to know when the associated
RootAdapter is changing and thus being able to find the highlighted
Preference
- also, add the correct Search key during indexing. She should
match the one created when adding dynamically the Preference
- last, increase to 400ms the delay to do the highlight

Change-Id: I3a1a81fdf5c8ab5f3aaab29f16ea9879ab6df056

src/com/android/settings/print/PrintSettingsFragment.java

@@ -565,7 +565,13 @@ public class PrintSettingsFragment extends SettingsPreferenceFragment
             final int serviceCount = services.size();
             for (int i = 0; i < serviceCount; i++) {
                 PrintServiceInfo service = services.get(i);
+
+                ComponentName componentName = new ComponentName(
+                        service.getResolveInfo().serviceInfo.packageName,
+                        service.getResolveInfo().serviceInfo.name);
+
                 SearchIndexableRaw indexable = new SearchIndexableRaw(context);
+                indexable.key = componentName.flattenToString();
                 indexable.title = service.getResolveInfo().loadLabel(packageManager).toString();
                 indexable.summaryOn = context.getString(R.string.print_feature_state_on);
                 indexable.summaryOff = context.getString(R.string.print_feature_state_off);