views: remove PlatformStyle combobox hooks

ui/views/style/platform_style.h

Index: ui/views/style/platform_style.h
diff --git a/ui/views/style/platform_style.h b/ui/views/style/platform_style.h
index 876dba51c3a2e52fc117278912606b9740c6ec75..ce39689172502c95ab133fe4aaa46b4f5b373f23 100644
--- a/ui/views/style/platform_style.h
+++ b/ui/views/style/platform_style.h
@@ -10,7 +10,6 @@
 #include "base/macros.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/controls/button/custom_button.h"
-#include "ui/views/controls/combobox/combobox.h"
 #include "ui/views/views_export.h"
 
 namespace views {
@@ -26,10 +25,6 @@ class VIEWS_EXPORT PlatformStyle {
   // Type used by LabelButton to map button states to text colors.
   using ButtonColorByState = SkColor[Button::STATE_COUNT];
 
-  // Padding to use on either side of the arrow for a Combobox when in
-  // Combobox::STYLE_NORMAL.
-  static const int kComboboxNormalArrowPadding;
-
   // Minimum size for platform-styled buttons (Button::STYLE_BUTTON).
   static const int kMinLabelButtonWidth;
   static const int kMinLabelButtonHeight;
@@ -71,13 +66,6 @@ class VIEWS_EXPORT PlatformStyle {
   // opens in the opposite direction.
   static const bool kMirrorBubbleArrowInRTLByDefault;
 
-  // Creates an ImageSkia containing the image to use for the combobox arrow.
-  // The |is_enabled| argument is true if the control the arrow is for is
-  // enabled, and false if the control is disabled. The |style| argument is the
-  // style of the combobox the arrow is being drawn for.
-  static gfx::ImageSkia CreateComboboxArrow(bool is_enabled,
-                                            Combobox::Style style);
-
   // Creates the default scrollbar for the given orientation.
   static std::unique_ptr<ScrollBar> CreateScrollBar(bool is_horizontal);