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)),
+      focus_ring_(nullptr),
       size_to_largest_label_(style_ == STYLE_NORMAL),
       weak_ptr_factory_(this) {
   ModelChanged();
 #if defined(OS_MACOSX)
   SetFocusBehavior(FocusBehavior::ACCESSIBLE_ONLY);
 #else
   SetFocusBehavior(FocusBehavior::ALWAYS);
 #endif
 
   UpdateBorder();
   if (UseMd()) {
     // set_background() takes ownership but takes a raw pointer.
     std::unique_ptr<Background> b =
         PlatformStyle::CreateComboboxBackground(GetArrowContainerWidth());
     set_background(b.release());
+    focus_ring_ = new FocusRing();
+    AddChildView(focus_ring_);
   }
 
   // Initialize the button images.
   Button::ButtonState button_states[] = {
     Button::STATE_DISABLED,
     Button::STATE_NORMAL,
     Button::STATE_HOVERED,
     Button::STATE_PRESSED,
   };
   for (int i = 0; i < 2; i++) {
@@ skipping 282 matching lines @@
   }
 }
 
 void Combobox::OnFocus() {
   if (GetInputMethod())
     GetInputMethod()->SetFocusedTextInputClient(GetPrefixSelector());
 
   View::OnFocus();
   // Border renders differently when focused.
   SchedulePaint();
+  if (UseMd())
+    focus_ring_->SetVisible(true);
 }
 
 void Combobox::OnBlur() {
   if (GetInputMethod())
     GetInputMethod()->DetachTextInputClient(GetPrefixSelector());
 
   if (selector_)
     selector_->OnViewBlur();
   // Border renders differently when focused.
   SchedulePaint();
+  if (UseMd())

[sky, 2016/10/03 23:53:15]

Is there a reason not to delegate focus_ring_ here?

[Evan Stade, 2016/10/04 01:04:55]

No reason.

Made a couple of statics to create and add/remove and destroy rings. (This also
addresses most of your other comments.)

+    focus_ring_->SetVisible(false);
 }
 
 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