Revert "[Settings] Convert to getSystemService(Class<T>)"

Revert submission 1645152-getSystemService(Class<T>)

Reason for revert: Fix JUnit test failure
Reverted Changes:
I1b4812044:[Settings] Convert to getSystemService(Class<T>)
I278951c24:[Settings] Support getSystemService(Class<T>)

Change-Id: I864a40f82ba9cb4170900ac0c1d77f781b17341f

src/com/android/settings/wifi/WifiAPITest.java

@@ -64,7 +64,7 @@ public class WifiAPITest extends SettingsPreferenceFragment implements
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
-        mWifiManager = getSystemService(WifiManager.class);
+        mWifiManager = (WifiManager) getSystemService(WIFI_SERVICE);
     }
 
     @Override