Switch Linux Auru ports over to POSIX SHM instead of legacy SYSV SHM.

ui/surface/transport_dib_posix.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.
-// Linux Aura and Chrome OS do too. This will change very soon.
-#if !defined(TOOLKIT_GTK) && !(defined(OS_LINUX) && defined(USE_AURA))
+#if !defined(TOOLKIT_GTK)
 
 #include <sys/stat.h>
 #include <unistd.h>
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/shared_memory.h"
 #include "base/posix/eintr_wrapper.h"
 #include "skia/ext/platform_canvas.h"
 
@@ skipping 87 matching lines @@
   return handle();
 #else
   return shared_memory_.id();
 #endif
 }
 
 TransportDIB::Handle TransportDIB::handle() const {
   return shared_memory_.handle();
 }
 
-#endif  // !defined(TOOLKIT_GTK) && !(defined(OS_LINUX) && defined(USE_AURA))
+#endif  // !defined(TOOLKIT_GTK)