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/MasterSwitchPreference.java

@@ -0,0 +1,102 @@
+/*
+ * 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.content.Context;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceViewHolder;
+import android.util.AttributeSet;
+import android.widget.CompoundButton;
+import android.widget.Switch;
+
+import com.android.settings.R;
+
+/**
+ * A custom preference that provides inline switch toggle. It has a mandatory field for title, and
+ * optional fields for icon and sub-text.
+ */
+public class MasterSwitchPreference extends Preference {
+
+    private Switch mSwitch;
+    private boolean mChecked;
+
+    public MasterSwitchPreference(Context context, AttributeSet attrs,
+            int defStyleAttr, int defStyleRes) {
+        super(context, attrs, defStyleAttr, defStyleRes);
+        init();
+    }
+
+    public MasterSwitchPreference(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+        init();
+    }
+
+    public MasterSwitchPreference(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        init();
+    }
+
+    public MasterSwitchPreference(Context context) {
+        super(context);
+        init();
+    }
+
+    @Override
+    public void onBindViewHolder(PreferenceViewHolder holder) {
+        super.onBindViewHolder(holder);
+        mSwitch = (Switch) holder.itemView.findViewById(R.id.switchWidget);
+        if (mSwitch != null) {
+            mSwitch.setChecked(mChecked);
+            mSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+                @Override
+                public void onCheckedChanged(CompoundButton button, boolean isChecked) {
+                    if (!callChangeListener(isChecked)) {
+                        button.setChecked(!isChecked);
+                    } else {
+                        persistBoolean(isChecked);
+                        mChecked = isChecked;
+                    }
+                }
+            });
+        }
+    }
+
+    public boolean isChecked() {
+        return isEnabled() && mChecked;
+    }
+
+    public void setChecked(boolean checked) {
+        mChecked = checked;
+        if (mSwitch != null) {
+            mSwitch.setChecked(checked);
+        }
+    }
+
+    public boolean isSwitchEnabled() {
+        return isEnabled() && mSwitch != null && mSwitch.isEnabled();
+    }
+
+    public void setSwitchEnabled(boolean enabled) {
+        if (mSwitch != null) {
+            mSwitch.setEnabled(enabled);
+        }
+    }
+
+    private void init() {
+        setWidgetLayoutResource(R.layout.preference_widget_master_switch);
+    }
+}