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

ppapi/proxy/video_source_resource.cc

 // Copyright (c) 2013 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 "ppapi/proxy/video_source_resource.h"
 
 #include "base/bind.h"
 #include "ipc/ipc_message.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/private/pp_video_frame_private.h"
@@ skipping 91 matching lines @@
     PP_TimeTicks timestamp) {
   // The callback may have been aborted by Close().
   if (TrackedCallback::IsPending(get_frame_callback_)) {
     int32_t result = reply_params.result();
     if (result == PP_OK &&
         PPB_ImageData_Shared::IsImageDataDescValid(image_desc)) {
       frame->timestamp = timestamp;
 
 #if defined(OS_ANDROID)
       frame->image_data = 0;
-#elif defined(OS_WIN) || defined(OS_MACOSX)
+#elif defined(TOOLKIT_GTK)
+      frame->image_data =
+          (new ImageData(image_data, image_desc, fd))->GetReference();
+#elif defined(OS_LINUX) || defined(OS_WIN) || defined(OS_MACOSX)
       base::SharedMemoryHandle handle;
       if (!reply_params.TakeSharedMemoryHandleAtIndex(0, &handle))
         frame->image_data = 0;
       frame->image_data =
           (new ImageData(image_data, image_desc, handle))->GetReference();
-#elif defined(OS_LINUX)
-      frame->image_data =
-          (new ImageData(image_data, image_desc, fd))->GetReference();
 #else
 #error Not implemented.
 #endif
     }
     get_frame_callback_->Run(result);
   }
 }
 
 }  // namespace proxy
 }  // namespace ppapi