Add a row in the network tray to inform users to turn Bluetooth on to enable Tether.

ash/system/bluetooth/tray_bluetooth.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/system/bluetooth/tray_bluetooth.h"
 
 #include <map>
 #include <memory>
 #include <set>
 #include <string>
@@ skipping 296 matching lines @@
     // present, also add a section header above the unpaired devices.
     if (discovered_not_paired_devices_.size() > 0) {
       if (num_paired_devices > 0)
         AddScrollListSubHeader(IDS_ASH_STATUS_TRAY_BLUETOOTH_UNPAIRED_DEVICES);
       AppendSameTypeDevicesToScrollList(discovered_not_paired_devices_, false,
                                         false, bluetooth_enabled);
     }
 
     // Show user Bluetooth state if there is no bluetooth devices in list.
     if (device_map_.size() == 0 && bluetooth_available && bluetooth_enabled) {
-      scroll_content()->AddChildView(
-          new InfoLabel(IDS_ASH_STATUS_TRAY_BLUETOOTH_DISCOVERING));
+      scroll_content()->AddChildView(TrayDetailsView::CreateInfoLabel(
+          IDS_ASH_STATUS_TRAY_BLUETOOTH_DISCOVERING));
     }
 
     // Focus the device which was focused before the device-list update.
     if (!focused_device_address.empty())
       FocusDeviceByAddress(focused_device_address);
 
     scroll_content()->InvalidateLayout();
   }
 
   void AppendSameTypeDevicesToScrollList(const BluetoothDeviceList& list,
@@ skipping 241 matching lines @@
     detailed_->Update();
 }
 
 void TrayBluetooth::OnBluetoothDiscoveringChanged() {
   if (!detailed_)
     return;
   detailed_->Update();
 }
 
 }  // namespace ash