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

ui/gfx/path_gtk.cc

 // Copyright (c) 2011 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/gfx/path.h"
 
 #include <gdk/gdk.h>
 
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.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 gfx {
 
 GdkRegion* Path::CreateNativeRegion() const {
   int point_count = getPoints(NULL, 0);
   if (point_count <= 1) {
     // NOTE: ideally this would return gdk_empty_region, but that returns a
     // region with nothing in it.
     return NULL;
   }
 
@@ skipping 24 matching lines @@
 }
 
 // static
 NativeRegion Path::SubtractRegion(NativeRegion r1, NativeRegion r2) {
   GdkRegion* copy = gdk_region_copy(r1);
   gdk_region_subtract(copy, r2);
   return copy;
 }
 
 }  // namespace gfx