Added a screen to configure wireless scanning

- Created "Scanning" preference screen

- Added overflow menu on "Location" settings to access "Scanning" settings

- Moved "Wi-Fi scanning always available" from Wi-Fi settings to "Scanning"
  settings

- Added "Bluetooth scanning always available" preference (UI only)

Change-Id: I85d8cd60ab309db5db9caee43f4b5a117192d904

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

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2015 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.preference.Preference;
+import android.preference.PreferenceScreen;
+import android.preference.SwitchPreference;
+import android.provider.Settings.Global;
+
+import com.android.settings.R;
+import com.android.settings.SettingsPreferenceFragment;
+
+/**
+ * A page that configures the background scanning settings for Wi-Fi and Bluetooth.
+ */
+public class ScanningSettings extends SettingsPreferenceFragment {
+    private static final String KEY_WIFI_SCAN_ALWAYS_AVAILABLE = "wifi_always_scanning";
+
+    @Override
+    public void onResume() {
+        super.onResume();
+        createPreferenceHierarchy();
+    }
+
+    private PreferenceScreen createPreferenceHierarchy() {
+        PreferenceScreen root = getPreferenceScreen();
+        if (root != null) {
+            root.removeAll();
+        }
+        addPreferencesFromResource(R.xml.location_scanning);
+        root = getPreferenceScreen();
+        initPreferences();
+        return root;
+    }
+
+    private void initPreferences() {
+        SwitchPreference scanAlwaysAvailable =
+            (SwitchPreference) findPreference(KEY_WIFI_SCAN_ALWAYS_AVAILABLE);
+        scanAlwaysAvailable.setChecked(Global.getInt(getContentResolver(),
+                    Global.WIFI_SCAN_ALWAYS_AVAILABLE, 0) == 1);
+    }
+
+    @Override
+    public boolean onPreferenceTreeClick(PreferenceScreen screen, Preference preference) {
+        String key = preference.getKey();
+        if (KEY_WIFI_SCAN_ALWAYS_AVAILABLE.equals(key)) {
+            Global.putInt(getContentResolver(),
+                    Global.WIFI_SCAN_ALWAYS_AVAILABLE,
+                    ((SwitchPreference) preference).isChecked() ? 1 : 0);
+        } else {
+            return super.onPreferenceTreeClick(screen, preference);
+        }
+        return true;
+    }
+}