Printing: Call PrintingContext::AskUserForSettings() on the UI thread for Linux

chrome/browser/printing/print_job_worker.h

 // Copyright (c) 2006-2008 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.
 
 #ifndef CHROME_BROWSER_PRINTING_PRINT_JOB_WORKER_H__
 #define CHROME_BROWSER_PRINTING_PRINT_JOB_WORKER_H__
 #pragma once
 
 #include "base/task.h"
 #include "base/thread.h"
@@ skipping 63 matching lines @@
   // Renders a page in the printer.
   void SpoolPage(PrintedPage& page);
 
   // Closes the job since spooling is done.
   void OnDocumentDone();
 
   // Discards the current document, the current page and cancels the printing
   // context.
   void OnFailure();
 
-#if defined(OS_MACOSX)
+#if defined(OS_MACOSX) || defined(USE_X11)
   // Asks the user for print settings. Must be called on the UI thread.
-  // Mac-only since Windows can display UI from non-main threads.
+  // Mac and Linux-only since Windows can display UI from non-main threads.
   void GetSettingsWithUI(gfx::NativeView parent_view,
                          int document_page_count,
                          bool has_selection);
 
   // The callback used by PrintingContext::GetSettingsWithUI() to notify this
   // object that the print settings are set.  This is needed in order to bounce
   // back into the IO thread for GetSettingsDone().
   void GetSettingsWithUIDone(PrintingContext::Result result);
 #endif
 
@@ skipping 20 matching lines @@
 
 template <>
 struct RunnableMethodTraits<printing::PrintJobWorker> {
   void RetainCallee(printing::PrintJobWorker* obj);
   void ReleaseCallee(printing::PrintJobWorker* obj);
  private:
   scoped_refptr<printing::PrintJobWorkerOwner> owner_;
 };
 
 #endif  // CHROME_BROWSER_PRINTING_PRINT_JOB_WORKER_H__