views combobox: use MD padding on Mac in MD mode

ui/views/controls/combobox/combobox.cc

Index: ui/views/controls/combobox/combobox.cc
diff --git a/ui/views/controls/combobox/combobox.cc b/ui/views/controls/combobox/combobox.cc
index 983a8077e9d600bf041a8cf351ce53fe477cdc5b..becceb5ba03d010d8c62f4a329cd8a10e34cefed 100644
--- a/ui/views/controls/combobox/combobox.cc
+++ b/ui/views/controls/combobox/combobox.cc
@@ -407,9 +407,11 @@ Combobox::Combobox(ui::ComboboxModel* model, Style style)
 
   UpdateBorder();
   // set_background() takes ownership but takes a raw pointer.
-  std::unique_ptr<Background> b =
-      PlatformStyle::CreateComboboxBackground(GetArrowContainerWidth());
-  set_background(b.release());
+  if (!UseMd()) {
+    std::unique_ptr<Background> b =
+        PlatformStyle::CreateComboboxBackground(GetArrowContainerWidth());
+    set_background(b.release());
+  }
 
   // Initialize the button images.
   Button::ButtonState button_states[] = {
@@ -788,6 +790,12 @@ void Combobox::PaintText(gfx::Canvas* canvas) {
 
   gfx::Rect text_bounds(x, y, text_width, text_height);
   AdjustBoundsForRTLUI(&text_bounds);
+  // TODO(ellyjones): This doesn't seem right. There's no particular reason why
+  // the text should need the rectangle underneath it filled first while none of
+  // the other drawn things need that. Also, drawing over with
+  // SK_ColorTRANSPARENT doesn't seem to suffice. Why?
+  if (UseMd())
+    canvas->FillRect(text_bounds, SK_ColorWHITE);
   canvas->DrawStringRect(text, font_list, text_color, text_bounds);
 
   gfx::Rect arrow_bounds(disclosure_arrow_offset, 0, GetArrowContainerWidth(),
@@ -968,8 +976,11 @@ PrefixSelector* Combobox::GetPrefixSelector() {
 }
 
 int Combobox::GetArrowContainerWidth() const {
+  const int kMdPaddingWidth = 8;

[Evan Stade, 2016/09/07 17:24:43]

this change seems fine

+  int arrow_pad = UseMd() ? kMdPaddingWidth
+                          : PlatformStyle::kComboboxNormalArrowPadding;
   int padding = style_ == STYLE_NORMAL
-                    ? PlatformStyle::kComboboxNormalArrowPadding * 2
+                    ? arrow_pad * 2
                     : kActionLeftPadding + kActionRightPadding;
   return ArrowSize().width() + padding;
 }