GTK: Adds #error statements to GTK code to root out unknown bots.

ui/native_theme/native_theme_gtk.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_gtk.h"
 
 #include <gtk/gtk.h>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "ui/gfx/skia_utils_gtk.h"
 
+#error "The GTK+ port will be deleted later this week. If you are seeing this, you are trying to compile it. Please check your gyp flags for 'use_aura=0' and remove them."
+
 namespace {
 
 const SkColor kInvalidColorIdColor = SkColorSetRGB(255, 0, 128);
 
 // Theme colors returned by GetSystemColor().
 
 // FocusableBorder:
 const SkColor kFocusedBorderColor = SkColorSetRGB(0x4D, 0x90, 0xFE);
 const SkColor kUnfocusedBorderColor = SkColorSetRGB(0xD9, 0xD9, 0xD9);
 
@@ skipping 76 matching lines @@
   return kInvalidColorIdColor;
 }
 
 NativeThemeGtk::NativeThemeGtk() {
 }
 
 NativeThemeGtk::~NativeThemeGtk() {
 }
 
 }  // namespace ui