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

ui/surface/transport_dib_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/surface/transport_dib.h"
 
 // Desktop GTK Linux builds use the old-style SYSV SHM based DIBs.
 
 #include <errno.h>
 #include <stdlib.h>
 #include <sys/ipc.h>
 #include <sys/shm.h>
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "skia/ext/platform_canvas.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/gfx/size.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."
+
 // The shmat system call uses this as it's invalid return address
 static void *const kInvalidAddress = (void*) -1;
 
 TransportDIB::TransportDIB()
     : address_(kInvalidAddress),
       x_shm_(0),
       display_(NULL),
       inflight_counter_(0),
       detached_(false),
       size_(0) {
@@ skipping 119 matching lines @@
     delete this;
 }
 
 void TransportDIB::Detach() {
   CHECK(!detached_);
   detached_ = true;
   if (!inflight_counter_)
     delete this;
 }