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

ui/base/native_theme/native_theme_gtk.cc

Index: ui/base/native_theme/native_theme_gtk.cc
diff --git a/ui/gfx/native_theme_gtk.cc b/ui/base/native_theme/native_theme_gtk.cc
similarity index 96%
rename from ui/gfx/native_theme_gtk.cc
rename to ui/base/native_theme/native_theme_gtk.cc
index 53d2636e065f6d428524e644370dbcac287156f1..d8eab303752fd4ae221367d657707a3a1e474752 100644
--- a/ui/gfx/native_theme_gtk.cc
+++ b/ui/base/native_theme/native_theme_gtk.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ui/gfx/native_theme_gtk.h"
+#include "ui/base/native_theme/native_theme_gtk.h"
 
 #include <gtk/gtk.h>
 
@@ -29,7 +29,7 @@ const SkColor kTextButtonHoverColor = kTextButtonEnabledColor;
 
 }  // namespace
 
-namespace gfx {
+namespace ui {
 
 // static
 const NativeTheme* NativeTheme::instance() {
@@ -84,4 +84,4 @@ NativeThemeGtk::NativeThemeGtk() {
 NativeThemeGtk::~NativeThemeGtk() {
 }
 
-}  // namespace gfx
+}  // namespace ui