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

src/com/android/settings/core/SliderPreferenceController.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package com.android.settings.core;
+
+import android.content.Context;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.SeekBarPreference;
+
+import com.android.settings.slices.SliceData;
+
+public abstract class SliderPreferenceController extends BasePreferenceController implements
+        Preference.OnPreferenceChangeListener {
+
+    public SliderPreferenceController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+    }
+
+    @Override
+    public boolean onPreferenceChange(Preference preference, Object newValue) {
+        return setSliderPosition((int) newValue);
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        ((SeekBarPreference) preference).setValue(getSliderPosition());
+    }
+
+    /**
+     * @return the value of the Slider's position based on the range: [0, maxSteps).
+     */
+    public abstract int getSliderPosition();
+
+    /**
+     * Set the slider to a new value.
+     *
+     * @param position of the slider.
+     * @return {@code true} if the position is successfully set.
+     */
+    public abstract boolean setSliderPosition(int position);
+
+    /**
+     * @return the number of steps supported by the slider.
+     */
+    public abstract int getMaxSteps();
+
+    @Override
+    public int getSliceType() {
+        return SliceData.SliceType.SLIDER;
+    }
+}

src/com/android/settings/core/TogglePreferenceController.java

@@ -58,7 +58,7 @@ public abstract class TogglePreferenceController extends BasePreferenceControlle
 
     @Override
     public final boolean onPreferenceChange(Preference preference, Object newValue) {
-        return setChecked((Boolean) newValue);
+        return setChecked((boolean) newValue);
     }
 
     @Override