Misc fixes to search and UI.

- Use prefContext to create preference.
- rename "Gestures" to "Gesture shortcuts"
- Add search keyword to individual gesture settings so when search
  "gesture" they also show up.
- call super() for all getNonIndexableKeys() in search provider

Fix: 38327387
Fix: 36621897
Fix: 36685646
Test: make RunSettingsRoboTests

Change-Id: Ia5ddfeae08cb27c278dfb8d2376594e21d8f283c

src/com/android/settings/datausage/DataUsageMeteredSettings.java

@@ -226,7 +226,7 @@ public class DataUsageMeteredSettings extends SettingsPreferenceFragment impleme
 
             @Override
             public List<String> getNonIndexableKeys(Context context) {
-                final ArrayList<String> result = new ArrayList<String>();
+                final List<String> result = super.getNonIndexableKeys(context);
                 if (!SHOW_MOBILE_CATEGORY || !hasReadyMobileRadio(context)) {
                     result.add("mobile");
                 }