Move more printing code off of the FILE thread.

chrome/browser/printing/print_dialog_cloud_win.cc

 // Copyright 2015 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 "chrome/browser/printing/print_dialog_cloud.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/base64.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/json/json_writer.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/task_scheduler/post_task.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/scoped_tabbed_browser_displayer.h"
 #include "chrome/common/chrome_switches.h"
 #include "components/cloud_devices/common/cloud_devices_urls.h"
 #include "components/google/core/browser/google_util.h"
 #include "content/public/browser/browser_context.h"
@@ skipping 70 matching lines @@
           content::Referrer(), WindowOpenDisposition::NEW_FOREGROUND_TAB,
           ui::PAGE_TRANSITION_AUTO_BOOKMARK, false));
   if (data && data->size()) {
     new PrintDataSetter(web_contents, data, print_job_title, print_ticket,
                         file_type);
   }
 }
 
 scoped_refptr<base::RefCountedMemory> ReadFile(
     const base::FilePath& path_to_file) {
-  DCHECK_CURRENTLY_ON(content::BrowserThread::FILE);
   scoped_refptr<base::RefCountedMemory> data;
   int64_t file_size = 0;
   if (base::GetFileSize(path_to_file, &file_size) && file_size != 0) {
     if (file_size > kMaxFileSize) {
       DLOG(WARNING) << " print data file too large to reserve space";
       return data;
     }
     std::string file_data;
     file_data.reserve(static_cast<size_t>(file_size));
     if (base::ReadFileToString(path_to_file, &file_data))
       data = base::RefCountedString::TakeString(&file_data);
   }
   base::DeleteFile(path_to_file, false);
   return data;
 }
 
 void CreatePrintDialogForFile(content::BrowserContext* browser_context,
                               const base::FilePath& path_to_file,
                               const base::string16& print_job_title,
                               const base::string16& print_ticket,
                               const std::string& file_type) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  content::BrowserThread::PostTaskAndReplyWithResult(
-      content::BrowserThread::FILE, FROM_HERE,
+  base::PostTaskWithTraitsAndReplyWithResult(
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::USER_BLOCKING},
       base::Bind(&ReadFile, path_to_file),
-      base::Bind(&CreatePrintDialog, browser_context,
-                 print_job_title, print_ticket, file_type));
+      base::Bind(&CreatePrintDialog, browser_context, print_job_title,
+                 print_ticket, file_type));
 }
 
 }  // namespace
 
 bool CreatePrintDialogFromCommandLine(Profile* profile,
                                       const base::CommandLine& command_line) {
   base::FilePath cloud_print_file =
       command_line.GetSwitchValuePath(switches::kCloudPrintFile);
   DCHECK(!cloud_print_file.empty());
   if (cloud_print_file.empty())
     return false;
   base::string16 print_job_title =
       command_line.GetSwitchValueNative(switches::kCloudPrintJobTitle);
   base::string16 print_job_print_ticket =
       command_line.GetSwitchValueNative(switches::kCloudPrintPrintTicket);
   std::string file_type =
       command_line.GetSwitchValueASCII(switches::kCloudPrintFileType);
   if (file_type.empty())
     file_type = "application/pdf";
   CreatePrintDialogForFile(profile, cloud_print_file, print_job_title,
                            print_job_print_ticket, file_type);
   return true;
 }
 
 }  // namespace print_dialog_cloud