Move the IconLoader to use the task scheduler.

chrome/browser/icon_loader_auralinux.cc

 // Copyright 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 "chrome/browser/icon_loader.h"
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/nix/mime_util_xdg.h"
 #include "ui/views/linux_ui/linux_ui.h"
 
 // static
 IconLoader::IconGroup IconLoader::GroupForFilepath(
     const base::FilePath& file_path) {
   return base::nix::GetFileMimeType(file_path);
 }
 
 // static
-content::BrowserThread::ID IconLoader::ReadIconThreadID() {
+scoped_refptr<base::TaskRunner> IconLoader::GetReadIconTaskRunner() {
   // ReadIcon() calls into views::LinuxUI and GTK2 code, so it must be on the UI
   // thread.
-  return content::BrowserThread::UI;
+  return content::BrowserThread::GetTaskRunnerForThread(
+      content::BrowserThread::UI);
 }
 
 void IconLoader::ReadIcon() {
   int size_pixels = 0;
   switch (icon_size_) {
     case IconLoader::SMALL:
       size_pixels = 16;
       break;
     case IconLoader::NORMAL:
       size_pixels = 32;
@@ skipping 11 matching lines @@
     image = base::MakeUnique<gfx::Image>(
         ui->GetIconForContentType(group_, size_pixels));
     if (image->IsEmpty())
       image = nullptr;
   }
 
   target_task_runner_->PostTask(
       FROM_HERE, base::BindOnce(callback_, base::Passed(&image), group_));
   delete this;
 }