Refactor MdFocusRing to make it easier to reuse on other controls.

ui/views/controls/combobox/combobox.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 "ui/views/controls/combobox/combobox.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 16 matching lines @@
 #include "ui/native_theme/common_theme.h"
 #include "ui/native_theme/native_theme.h"
 #include "ui/native_theme/native_theme_aura.h"
 #include "ui/resources/grit/ui_resources.h"
 #include "ui/views/animation/flood_fill_ink_drop_ripple.h"
 #include "ui/views/animation/ink_drop_highlight.h"
 #include "ui/views/background.h"
 #include "ui/views/controls/button/custom_button.h"
 #include "ui/views/controls/button/label_button.h"
 #include "ui/views/controls/combobox/combobox_listener.h"
+#include "ui/views/controls/focus_ring.h"
 #include "ui/views/controls/focusable_border.h"
 #include "ui/views/controls/menu/menu_config.h"
 #include "ui/views/controls/menu/menu_model_adapter.h"
 #include "ui/views/controls/menu/menu_runner.h"
 #include "ui/views/controls/prefix_selector.h"
 #include "ui/views/controls/textfield/textfield.h"
 #include "ui/views/mouse_constants.h"
 #include "ui/views/painter.h"
 #include "ui/views/resources/grit/views_resources.h"
 #include "ui/views/style/platform_style.h"
@@ skipping 338 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(ComboboxMenuModel);
 };
 
 ////////////////////////////////////////////////////////////////////////////////
 // Combobox, public:
 
 Combobox::Combobox(ui::ComboboxModel* model, Style style)
     : model_(model),
       style_(style),
-      listener_(NULL),
+      listener_(nullptr),
       selected_index_(style == STYLE_ACTION ? 0 : model_->GetDefaultIndex()),
       invalid_(false),
       menu_model_(new ComboboxMenuModel(this, model)),
       text_button_(new TransparentButton(this, style_ == STYLE_ACTION)),
       arrow_button_(new TransparentButton(this, style_ == STYLE_ACTION)),
       size_to_largest_label_(style_ == STYLE_NORMAL),
       weak_ptr_factory_(this) {
   ModelChanged();
 #if defined(OS_MACOSX)
   SetFocusBehavior(FocusBehavior::ACCESSIBLE_ONLY);
@@ skipping 302 matching lines @@
   }
 }
 
 void Combobox::OnFocus() {
   if (GetInputMethod())
     GetInputMethod()->SetFocusedTextInputClient(GetPrefixSelector());
 
   View::OnFocus();
   // Border renders differently when focused.
   SchedulePaint();
+  if (UseMd())
+    FocusRing::Install(this);
 }
 
 void Combobox::OnBlur() {
   if (GetInputMethod())
     GetInputMethod()->DetachTextInputClient(GetPrefixSelector());
 
   if (selector_)
     selector_->OnViewBlur();
   // Border renders differently when focused.
   SchedulePaint();
+  if (UseMd())
+    FocusRing::Uninstall(this);
 }
 
 void Combobox::GetAccessibleState(ui::AXViewState* state) {
   state->role = ui::AX_ROLE_COMBO_BOX;
   state->name = accessible_name_;
   state->value = model_->GetItemAt(selected_index_);
   state->index = selected_index_;
   state->count = model_->GetItemCount();
 }
 
@@ skipping 254 matching lines @@
   const int kMdPaddingWidth = 8;
   int arrow_pad = UseMd() ? kMdPaddingWidth
                           : PlatformStyle::kComboboxNormalArrowPadding;
   int padding = style_ == STYLE_NORMAL
                     ? arrow_pad * 2
                     : kActionLeftPadding + kActionRightPadding;
   return ArrowSize().width() + padding;
 }
 
 }  // namespace views