Use fragment for input preference screen

This CL introduces a common abstract class, SunScreenFragment, for
PreferenceFragment that implements a PreferenceScreen of the main
settings preference screen.

Bug: 16522808
Change-Id: I11fba71b5e9f96208b261e0c0314de8a41720d0f
diff --git a/java/src/com/android/inputmethod/latin/settings/SettingsActivity.java b/java/src/com/android/inputmethod/latin/settings/SettingsActivity.java
index c899507..c7b9dcd 100644
--- a/java/src/com/android/inputmethod/latin/settings/SettingsActivity.java
+++ b/java/src/com/android/inputmethod/latin/settings/SettingsActivity.java
@@ -35,8 +35,7 @@
         return intent;
     }
 
-    // TODO: Uncomment the override annotation once we start using SDK version 19.
-    // @Override
+    @Override
     public boolean isValidFragment(String fragmentName) {
         return FragmentUtils.isValidFragment(fragmentName);
     }