Introduce boolean flag to show/hide Location Scanning preference.

This introduce one new flag:
config_show_location_scanning

Which when set to false, will hide "Scanning" in Location preference.

Some OEMs may control Bluetooth/Wi-Fi scanning themselves, so they may
want to hide the page from users.

Bug: 62418710
Test: make RunSettingsRoboTests
ROBOTEST_FILTER=LocationScanningPreferenceControllerTest

Change-Id: I19f0020a2c94f70b3b7956529f57af098ccc79fd

src/com/android/settings/location/LocationScanningPreferenceController.java

@@ -0,0 +1,41 @@
+/*
+ * 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.location;
+
+import android.content.Context;
+
+import com.android.settings.core.BasePreferenceController;
+import com.android.settings.R;
+
+import android.support.annotation.VisibleForTesting;
+
+
+public class LocationScanningPreferenceController extends BasePreferenceController {
+
+    @VisibleForTesting static final String KEY_LOCATION_SCANNING = "location_scanning";
+
+    public LocationScanningPreferenceController(Context context) {
+        super(context, KEY_LOCATION_SCANNING);
+    }
+
+    @AvailabilityStatus
+    public int getAvailabilityStatus() {
+        return mContext.getResources().getBoolean(R.bool.config_show_location_scanning)
+                ? AVAILABLE
+                : DISABLED_UNSUPPORTED;
+    }
+}