ui: Move NativeTheme files into ui/base/native_theme/ directory.

ui/views/controls/menu/menu_separator_views.cc

Index: ui/views/controls/menu/menu_separator_views.cc
diff --git a/ui/views/controls/menu/menu_separator_views.cc b/ui/views/controls/menu/menu_separator_views.cc
index 484825f762cad918c3afbde604e563a0e0fd9c07..1ef788d4f806af65109266f504da5e64b2a70a62 100644
--- a/ui/views/controls/menu/menu_separator_views.cc
+++ b/ui/views/controls/menu/menu_separator_views.cc
@@ -6,7 +6,7 @@
 
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/canvas.h"
-#include "ui/gfx/native_theme.h"
+#include "ui/base/native_theme/native_theme.h"
 #include "ui/views/controls/menu/menu_config.h"
 
 namespace {
@@ -19,8 +19,8 @@ namespace views {
 
 void MenuSeparator::OnPaint(gfx::Canvas* canvas) {
   canvas->FillRect(gfx::Rect(0, height() / 2, width(), kSeparatorHeight),
-      gfx::NativeTheme::instance()->GetSystemColor(
-          gfx::NativeTheme::kColorId_MenuSeparatorColor));
+      ui::NativeTheme::instance()->GetSystemColor(
+          ui::NativeTheme::kColorId_MenuSeparatorColor));
 }
 
 gfx::Size MenuSeparator::GetPreferredSize() {