Add Slider template for Slices

Add the Seekbar preference equivalent
to the TwoStatePreference (toggle) preference
controller abstract controller.

Change-Id: I6ff91f2f72a7f72c18ddbc27b2b1fda4b6ce6ca9
Fixes: 67996707
Test: Robotests

tests/robotests/src/com/android/settings/slices/SliceBuilderUtilsTest.java

@@ -28,6 +28,7 @@ import android.util.Pair;
 
 import com.android.settings.R;
 import com.android.settings.core.BasePreferenceController;
+import com.android.settings.testutils.FakeSliderController;
 import com.android.settings.testutils.FakeToggleController;
 import com.android.settings.testutils.SettingsRobolectricTestRunner;
 
@@ -68,6 +69,14 @@ public class SliceBuilderUtilsTest {
         assertThat(slice).isNotNull(); // TODO improve test for Slice content
     }
 
+    @Test
+    public void testSliderSlice_returnsSeekBarSlice() {
+        final Slice slice = SliceBuilderUtils.buildSlice(mContext, getDummyData(
+                FakeSliderController.class));
+
+        assertThat(slice).isNotNull();
+    }
+
     @Test
     public void testUriBuilder_oemAuthority_intentPath_returnsValidSliceUri() {
         Uri expectedUri = new Uri.Builder()