MacViews: draw combobox arrow backgrounds

ui/views/controls/combobox/combobox.h

 // 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.
 
 #ifndef UI_VIEWS_CONTROLS_COMBOBOX_COMBOBOX_H_
 #define UI_VIEWS_CONTROLS_COMBOBOX_COMBOBOX_H_
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/strings/string16.h"
@@ skipping 88 matching lines @@
 
   // Overridden from PrefixDelegate:
   int GetRowCount() override;
   int GetSelectedRow() override;
   void SetSelectedRow(int row) override;
   base::string16 GetTextForRow(int row) override;
 
   // Overriden from ButtonListener:
   void ButtonPressed(Button* sender, const ui::Event& event) override;
 
+  int GetArrowButtonWidth() const;

[tapted, 2016/03/22 23:04:32]

nit: move up before overrides

also comment - something to distinguish from just ArrowSize().width(), maybe

  // Width of the button containing the disclosure arrow (arrow size, plus
padding).

(or we could call drop arrow completely and call it the
GetDisclosureButtonWidth(), but I was a bit confused when I first saw
`disclosure`, so I'm not sure I like that)

[Elly Fong-Jones, 2016/03/23 18:07:44]

Done.

+
  private:
   friend class test::ComboboxTestApi;
 
   class ComboboxMenuModelAdapter;
 
   // Updates the border according to the current state.
   void UpdateBorder();
 
   // Given bounds within our View, this helper mirrors the bounds if necessary.
   void AdjustBoundsForRTLUI(gfx::Rect* rect) const;
@@ skipping 82 matching lines @@
 
   // Used for making calbacks.
   base::WeakPtrFactory<Combobox> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Combobox);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_COMBOBOX_COMBOBOX_H_