Add new preference class MasterSwitchPreference.

- Add a new preference type that has Title and optional summary on the
  left, and a toggle switch on the right. Clicking the left part of the
  preference will open a settings screen.
- Update Connected devices->Bluetooth to use this new preference.
- Refactor BluetoothSettings and BluetoothEnabler to share code between
  the new bluetooth preference controller and the bluetooth setting.

Bug: 34280769
Test: make RunSettingsRoboTests
Change-Id: I109ecdba640ecdd4748a6e5b2b4f4c47cbf653fd

src/com/android/settings/widget/MasterSwitchController.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2017 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.widget;
+
+import android.support.v7.preference.Preference;
+
+/*
+ * The switch controller that is used to update the switch widget in the MasterSwitchPreference
+ * layout.
+ */
+public class MasterSwitchController extends SwitchWidgetController implements
+    Preference.OnPreferenceChangeListener {
+
+    private final MasterSwitchPreference mPreference;
+
+    public MasterSwitchController(MasterSwitchPreference preference) {
+        mPreference = preference;
+    }
+
+    @Override
+    public void updateTitle(boolean isChecked) {
+    }
+
+    @Override
+    public void startListening() {
+        mPreference.setOnPreferenceChangeListener(this);
+    }
+
+    @Override
+    public void stopListening() {
+        mPreference.setOnPreferenceChangeListener(null);
+    }
+
+    @Override
+    public void setChecked(boolean checked) {
+        mPreference.setChecked(checked);
+    }
+
+    @Override
+    public boolean isChecked() {
+        return mPreference.isChecked();
+    }
+
+    @Override
+    public void setEnabled(boolean enabled) {
+        mPreference.setSwitchEnabled(enabled);
+    }
+
+    @Override
+    public boolean onPreferenceChange(Preference preference, Object newValue) {
+        if (mListener != null) {
+            return mListener.onSwitchToggled((Boolean) newValue);
+        }
+        return false;
+    }
+}