Improve search indexing time.

- Some import clean up.
- Add timing log to track indexing time breakdown.
- Remove isAvailable() from UserDictionaryPreferenceController.

Bug: 36391685
Test: rebuild
Change-Id: If154c5dafba5d21cb1020497c44fbf67f03ad820

src/com/android/settings/language/UserDictionaryPreferenceController.java

@@ -39,10 +39,7 @@ public class UserDictionaryPreferenceController extends AbstractPreferenceContro
 
     @Override
     public boolean isAvailable() {
-        final TreeSet<String> localeSet = getDictionaryLocales();
-        // The locale list is null if and only if the user dictionary service is
-        // not present or disabled. In this case we need to remove the preference.
-        return localeSet != null;
+        return true;
     }
 
     @Override