Add indexing for Notifications preferences

- also add indexing of CheckBoxPreferences
- also some code cleaning

Change-Id: I2943caaec3d64fb2a6be85168454fc76fe572afe
diff --git a/src/com/android/settings/SettingsActivity.java b/src/com/android/settings/SettingsActivity.java
index c2b01cf..206865f 100644
--- a/src/com/android/settings/SettingsActivity.java
+++ b/src/com/android/settings/SettingsActivity.java
@@ -386,16 +386,13 @@
         // Cache the search query (can be overriden by the OnQueryTextListener)
         final String query = mSearchQuery;
 
-        // Associate searchable configuration with the SearchView
-        SearchManager searchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE);
-        mSearchView = (SearchView) menu.findItem(R.id.search).getActionView();
+        mSearchMenuItem = menu.findItem(R.id.search);
+        mSearchView = (SearchView) mSearchMenuItem.getActionView();
 
+        mSearchMenuItem.setOnActionExpandListener(this);
         mSearchView.setOnQueryTextListener(this);
         mSearchView.setOnCloseListener(this);
 
-        mSearchMenuItem = menu.findItem(R.id.search);
-        mSearchMenuItem.setOnActionExpandListener(this);
-
         if (mSearchMenuItemExpanded) {
             mSearchMenuItem.expandActionView();
         }