Try to get rid of all direct references to particular native themes.

ui/native_theme/native_theme_android.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/native_theme/native_theme_android.h"
 
 #include "base/logging.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace ui {
 
 namespace {
 // These are the default dimensions of radio buttons and checkboxes on Android.
 const int kCheckboxAndRadioWidth = 16;
 const int kCheckboxAndRadioHeight = 16;
 }
 
 #if !defined(USE_AURA)
 // static
 NativeTheme* NativeTheme::GetInstanceForWeb() {
   return NativeThemeAndroid::instance();
 }
+
+NativeTheme* NativeTheme::GetInstanceForNativeUi() {
+  NOTREACHED();
+  return nullptr;
+}
 #endif
 
 // static
 NativeThemeAndroid* NativeThemeAndroid::instance() {
   CR_DEFINE_STATIC_LOCAL(NativeThemeAndroid, s_native_theme, ());
   return &s_native_theme;
 }
 
 gfx::Size NativeThemeAndroid::GetPartSize(Part part,
                                           State state,
@@ skipping 14 matching lines @@
              rect->bottom() - 1);
 }
 
 NativeThemeAndroid::NativeThemeAndroid() {
 }
 
 NativeThemeAndroid::~NativeThemeAndroid() {
 }
 
 }  // namespace ui