Move the IconLoader to use the task scheduler.

chrome/browser/icon_loader_win.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 "chrome/browser/icon_loader.h"
 
 #include <windows.h>
 #include <shellapi.h>
 
 #include "base/bind.h"
@@ skipping 12 matching lines @@
   if (file_path.MatchesExtension(L".exe") ||
       file_path.MatchesExtension(L".dll") ||
       file_path.MatchesExtension(L".ico")) {
     return file_path.value();
   }
 
   return file_path.Extension();
 }
 
 // static
-content::BrowserThread::ID IconLoader::ReadIconThreadID() {
-  return content::BrowserThread::FILE;
+bool IconLoader::ReadIconRequiresUIThread() {
+  return false;
 }
 
 void IconLoader::ReadIcon() {
   int size = 0;
   switch (icon_size_) {
     case IconLoader::SMALL:
       size = SHGFI_SMALLICON;
       break;
     case IconLoader::NORMAL:
       size = 0;
@@ skipping 19 matching lines @@
       image_skia.MakeThreadSafe();
       image = base::MakeUnique<gfx::Image>(image_skia);
       DestroyIcon(file_info.hIcon);
     }
   }
 
   target_task_runner_->PostTask(
       FROM_HERE, base::Bind(callback_, base::Passed(&image), group_));
   delete this;
 }