[Settings] Support getSystemService(Class<T>)

Add getSystemService(Class<T>) to align the capability with framework
part.

Bug: 179640862
Test: local
Change-Id: I278951c2402aa8551cee37923f45626ab1830dd3
diff --git a/src/com/android/settings/SettingsPreferenceFragment.java b/src/com/android/settings/SettingsPreferenceFragment.java
index 659ada4..14402a7 100644
--- a/src/com/android/settings/SettingsPreferenceFragment.java
+++ b/src/com/android/settings/SettingsPreferenceFragment.java
@@ -439,6 +439,13 @@
     }
 
     /**
+     * Returns the specified system service from the owning Activity.
+     */
+    protected <T> T getSystemService(final Class<T> serviceClass) {
+        return getActivity().getSystemService(serviceClass);
+    }
+
+    /**
      * Returns the PackageManager from the owning Activity.
      */
     protected PackageManager getPackageManager() {