Keep focused device in Bluetooth device list when the list is refreshed.

ash/common/system/chromeos/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/common/system/chromeos/bluetooth/tray_bluetooth.h"
 
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/system/tray/hover_highlight_view.h"
 #include "ash/common/system/tray/system_tray.h"
 #include "ash/common/system/tray/system_tray_delegate.h"
@@ skipping 251 matching lines @@
   }
 
   void UpdateHeaderEntry() {
     bool is_bluetooth_enabled =
         WmShell::Get()->system_tray_delegate()->GetBluetoothEnabled();
     if (toggle_)
       toggle_->SetIsOn(is_bluetooth_enabled, true);
   }
 
   void UpdateDeviceScrollList() {
+    std::string focused_device_address = GetFocusedDeviceAddress();
+
     device_map_.clear();
     scroll_content()->RemoveAllChildViews(true);
 
     SystemTrayDelegate* delegate = WmShell::Get()->system_tray_delegate();
     bool bluetooth_enabled = delegate->GetBluetoothEnabled();
     bool bluetooth_available = delegate->GetBluetoothAvailable();
 
     // If Bluetooth is disabled, show a panel which only indicates that it is
     // disabled, instead of the scroller with Bluetooth devices.
     if (bluetooth_enabled) {
@@ skipping 29 matching lines @@
     if (device_map_.size() == 0) {
       if (bluetooth_available && bluetooth_enabled) {
         HoverHighlightView* container = new HoverHighlightView(this);
         container->AddLabel(l10n_util::GetStringUTF16(
                                 IDS_ASH_STATUS_TRAY_BLUETOOTH_DISCOVERING),
                             gfx::ALIGN_LEFT, false);
         scroll_content()->AddChildView(container);
       }
     }
 
+    // Focus the device which was focused before the device-list update.
+    if (!focused_device_address.empty())
+      FocusDeviceByAddress(focused_device_address);

[fukino, 2017/03/16 14:20:15]

Here, I restore the focus based on the device address rather than index in the
list.
I believe this is better considering the case when the list is long and the
number of upper items from the focused item changes.
However, when the focused item disappears from the list, the focus will be
reset. I assume it is a rare case, but WDYT?

[tdanderson, 2017/03/16 20:40:14]

Sounds good to me, I think focusing based on address is the right way to do it.
And if the focused element disappears, then I think resetting focus is perfectly
reasonable.

+
     scroll_content()->InvalidateLayout();
   }
 
   void AppendSameTypeDevicesToScrollList(const BluetoothDeviceList& list,
                                          bool highlight,
                                          bool checked,
                                          bool enabled) {
     for (size_t i = 0; i < list.size(); ++i) {
       HoverHighlightView* container = nullptr;
       gfx::ImageSkia icon_image = CreateVectorIcon(
@@ skipping 210 matching lines @@
         kDisabledPanelLabelBaselineY - label->GetBaseline(), 0, 0, 0));
     container->AddChildView(label);
 
     // Make top padding of the icon equal to the height of the label so that the
     // icon is vertically aligned to center of the container.
     image_view->SetBorder(
         views::CreateEmptyBorder(label->GetPreferredSize().height(), 0, 0, 0));
     return container;
   }
 
+  std::string GetFocusedDeviceAddress() {
+    for (auto& view_and_address : device_map_) {
+      if (view_and_address.first->HasFocus())
+        return view_and_address.second;
+    }
+    return std::string();
+  }
+
+  void FocusDeviceByAddress(const std::string& address) {
+    for (auto& view_and_address : device_map_) {
+      if (view_and_address.second == address) {
+        view_and_address.first->RequestFocus();
+        return;
+      }
+    }
+  }
+
   LoginStatus login_;
 
   std::map<views::View*, std::string> device_map_;
 
   BluetoothDeviceList connected_devices_;
   BluetoothDeviceList connecting_devices_;
   BluetoothDeviceList paired_not_connected_devices_;
   BluetoothDeviceList discovered_not_paired_devices_;
 
   views::ToggleButton* toggle_;
@@ skipping 61 matching lines @@
     detailed_->Update();
 }
 
 void TrayBluetooth::OnBluetoothDiscoveringChanged() {
   if (!detailed_)
     return;
   detailed_->Update();
 }
 
 }  // namespace ash