Replace hard-coded colors from ui::NativeTheme for consistency and accessibility.

chrome/browser/ui/autofill/autofill_popup_controller.h

Index: chrome/browser/ui/autofill/autofill_popup_controller.h
diff --git a/chrome/browser/ui/autofill/autofill_popup_controller.h b/chrome/browser/ui/autofill/autofill_popup_controller.h
index 5bede9c60c457b724225c0637a4eeb994d33e13b..c9aec43f61bde65157c3d88dd5d74b8f0c8a022a 100644
--- a/chrome/browser/ui/autofill/autofill_popup_controller.h
+++ b/chrome/browser/ui/autofill/autofill_popup_controller.h
@@ -14,6 +14,7 @@
 #include "build/build_config.h"
 #include "chrome/browser/ui/autofill/autofill_popup_view_delegate.h"
 #include "third_party/skia/include/core/SkColor.h"
+#include "ui/native_theme/native_theme.h"
 
 namespace autofill {
 
@@ -46,9 +47,10 @@ class AutofillPopupController : public AutofillPopupViewDelegate {
   // Removes the suggestion at the given index.
   virtual bool RemoveSuggestion(int index) = 0;
 
-  // Returns the background color of the row item according to its |index|, or
-  // transparent if the default popup background should be used.
-  virtual SkColor GetBackgroundColorForRow(int index) const = 0;
+  // Returns the background color ID of the row item according to its |index|,
+  // or default popup background otherwise.
+  virtual ui::NativeTheme::ColorId GetBackgroundColorIDForRow(
+      int index) const = 0;
 
   // Returns the index of the selected line. A line is "selected" when it is
   // hovered or has keyboard focus.