Change to use the expand button in support lib.

- functionality for hiding portions of the preferences in the preference
screen is added to the support lib. So, changing the settings
implementation to use the feature from the support lib instead.
- remove ProgressiveDisclosureMixin and the related code

Fixes: 63985174
Test: make RunSettingsRoboTests
Change-Id: Ib1d39b2db93d78a56c7adf90abcae5226f9564c2

tests/robotests/src/com/android/settings/dashboard/DashboardFragmentTest.java

@@ -67,8 +67,6 @@ public class DashboardFragmentTest {
     private DashboardCategory mDashboardCategory;
     @Mock
     private FakeFeatureFactory mFakeFeatureFactory;
-    @Mock
-    private ProgressiveDisclosureMixin mDisclosureMixin;
     private TestFragment mTestFragment;
 
     @Before
@@ -79,9 +77,6 @@ public class DashboardFragmentTest {
         mDashboardCategory.tiles = new ArrayList<>();
         mDashboardCategory.tiles.add(new Tile());
         mTestFragment = new TestFragment(ShadowApplication.getInstance().getApplicationContext());
-        when(mFakeFeatureFactory.dashboardFeatureProvider.getProgressiveDisclosureMixin(
-                nullable(Context.class), eq(mTestFragment), nullable(Bundle.class)))
-                .thenReturn(mDisclosureMixin);
         when(mFakeFeatureFactory.dashboardFeatureProvider
                 .getTilesForCategory(nullable(String.class)))
                 .thenReturn(mDashboardCategory);
@@ -110,8 +105,7 @@ public class DashboardFragmentTest {
                 .thenReturn("test_key");
         mTestFragment.onCreatePreferences(new Bundle(), "rootKey");
 
-        verify(mDisclosureMixin).addPreference(nullable(PreferenceScreen.class),
-                nullable(Preference.class));
+        verify(mTestFragment.mScreen).addPreference(nullable(Preference.class));
     }
 
     @Test