Update Network & internet->Wi-Fi to use MasterSwitchPreference.

- Add a preference controller for Network & internet->Wi-Fi to control
  the preference toggling and summary update.
- Refactor WifiSettings and WifiEnabler to share code between the new
  wifi preference controller and the wifi setting.
- Refactor BluetoothSummaryHelper to have a common base class with the
  WifiSummaryHelper.
- Rename the summary helper to summary updater.

Bug: 34280769
Test: make RunSettingsRoboTests
Change-Id: I00ebfc161bcef89331bb41ba405ed8cb8232d248

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

@@ -17,6 +17,8 @@
 package com.android.settings.widget;
 
 import android.support.v7.preference.Preference;
+import android.widget.Switch;
+import com.android.settingslib.RestrictedLockUtils.EnforcedAdmin;
 
 /*
  * The switch controller that is used to update the switch widget in the MasterSwitchPreference
@@ -67,4 +69,14 @@ public class MasterSwitchController extends SwitchWidgetController implements
         }
         return false;
     }
+
+    @Override
+    public void setDisabledByAdmin(EnforcedAdmin admin) {
+        mPreference.setDisabledByAdmin(admin);
+    }
+
+    @Override
+    public Switch getSwitch() {
+        return mPreference.getSwitch();
+    }
 }