Move the IconLoader to use the task scheduler.

chrome/browser/icon_loader.h

 // 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.
 
 #ifndef CHROME_BROWSER_ICON_LOADER_H_
 #define CHROME_BROWSER_ICON_LOADER_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 48 matching lines @@
  private:
   IconLoader(const base::FilePath& file_path,
              IconSize size,
              IconLoadedCallback callback);
 
   ~IconLoader();
 
   // Given a file path, get the group for the given file.
   static IconGroup GroupForFilepath(const base::FilePath& file_path);
 
-  // The thread ReadIcon() should be called on.
-  static content::BrowserThread::ID ReadIconThreadID();
+  // Whether ReadIcon() must be called on the UI thread.
+  static bool ReadIconRequiresUIThread();
 
   void ReadGroup();
   void OnReadGroup();
   void ReadIcon();
 
   // The task runner object of the thread in which we notify the delegate.
   scoped_refptr<base::SingleThreadTaskRunner> target_task_runner_;
 
   base::FilePath file_path_;
 
   IconGroup group_;
 
   IconSize icon_size_;
 
   IconLoadedCallback callback_;
 
   DISALLOW_COPY_AND_ASSIGN(IconLoader);
 };
 
 #endif  // CHROME_BROWSER_ICON_LOADER_H_