Fix robo test compile error.

    @Mock WallpaperSetter mMockWallpaperSetter;

    private OverlayManagerMocks mMockOmHelper;

    private ThemeManager mThemeManager;

    private Activity mActivity;

    private FragmentActivity mActivity;

    @Before

    public void setUp() {

        MockitoAnnotations.initMocks(this);

        Activity activity = Robolectric.buildActivity(FragmentActivity.class).get();

        FragmentActivity activity = Robolectric.buildActivity(FragmentActivity.class).get();

        mActivity = spy(activity);

        mMockOmHelper = new OverlayManagerMocks();

        mMockOmHelper.setUpMock(mMockOm);