MenuButton: support Mac look & feel

ui/views/controls/button/menu_button.h

Index: ui/views/controls/button/menu_button.h
diff --git a/ui/views/controls/button/menu_button.h b/ui/views/controls/button/menu_button.h
index 696a94146f3f9868e01e2eca55a00dfab53f5e8e..2883149f185e7d051fd726ab1eb40421685a2863 100644
--- a/ui/views/controls/button/menu_button.h
+++ b/ui/views/controls/button/menu_button.h
@@ -53,12 +53,6 @@ class VIEWS_EXPORT MenuButton : public LabelButton {
              bool show_menu_marker);
   ~MenuButton() override;
 
-  bool show_menu_marker() const { return show_menu_marker_; }
-  void set_menu_marker(const gfx::ImageSkia* menu_marker) {
-    menu_marker_ = menu_marker;
-  }
-  const gfx::ImageSkia* menu_marker() const { return menu_marker_; }
-
   const gfx::Point& menu_offset() const { return menu_offset_; }
   void set_menu_offset(int x, int y) { menu_offset_.SetPoint(x, y); }
 
@@ -102,6 +96,10 @@ class VIEWS_EXPORT MenuButton : public LabelButton {
   // Offset of the associated menu position.
   gfx::Point menu_offset_;
 
+  // Returns the width of the "shoulder" of the menubutton, which is the area
+  // containing the menu marker, and any padding surrounding it.
+  int GetShoulderWidth() const;

[tapted, 2016/04/26 05:05:57]

can this be made private:?

[Elly Fong-Jones, 2016/04/26 17:41:25]

Done.

+
  private:
   friend class PressedLock;
 
@@ -128,10 +126,7 @@ class VIEWS_EXPORT MenuButton : public LabelButton {
   MenuButtonListener* listener_;
 
   // Whether or not we're showing a drop marker.
-  bool show_menu_marker_;
-
-  // The down arrow used to differentiate the menu button from normal buttons.
-  const gfx::ImageSkia* menu_marker_;
+  const bool show_menu_marker_;
 
   // If non-null the destructor sets this to true. This is set while the menu is
   // showing and used to detect if the menu was deleted while running.
@@ -148,6 +143,10 @@ class VIEWS_EXPORT MenuButton : public LabelButton {
   // programmatically show a menu on a disabled button.
   bool should_disable_after_press_;
 
+  // The images to draw for the menu marker, if |show_menu_marker_| is true.
+  gfx::ImageSkia enabled_marker_image_;
+  gfx::ImageSkia disabled_marker_image_;

[tapted, 2016/04/26 05:05:57]

Since the default PlatformStyle ignores the `enabled` argument, and it's rare
for a particular combobox to become disabled/enabled after being drawn once, I
think we should just have one marker_image_ - both here and in combobox.
Instead, just update the image it in an override of View::OnEnabledChanged [that
also calls the superclass impl].

also: (nit) move up to the previous location, below |show_menu_marker_|

[Elly Fong-Jones, 2016/04/26 17:41:25]

Done.

+
   base::WeakPtrFactory<MenuButton> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MenuButton);