linux_aura: run IconLoader::ReadIcon on the UI thread.

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 "build/build_config.h"
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop_proxy.h"
+#include "content/public/browser/browser_thread.h"
 #include "ui/gfx/image/image.h"
 
 #if defined(OS_WIN)
 // On Windows, we group files by their extension, with several exceptions:
 // .dll, .exe, .ico. See IconManager.h for explanation.
 typedef std::wstring IconGroupID;
 #elif defined(OS_POSIX)
 // On POSIX, we group files by MIME type.
 typedef std::string IconGroupID;
 #endif
@@ skipping 43 matching lines @@
 
   virtual ~IconLoader();
 
   // Get the identifying string for the given file. The implementation
   // is in icon_loader_[platform].cc.
   static IconGroupID ReadGroupIDFromFilepath(const base::FilePath& path);
 
   // Some icons (exe's on windows) can change as they're loaded.
   static bool IsIconMutableFromFilepath(const base::FilePath& path);
 
+  // The thread ReadIcon() should be called on.
+  static content::BrowserThread::ID ReadIconThreadID();
+
   void ReadGroup();
   void OnReadGroup();
   void ReadIcon();
 
   void NotifyDelegate();
 
   // The message loop object of the thread in which we notify the delegate.
   scoped_refptr<base::MessageLoopProxy> target_message_loop_;
 
   base::FilePath file_path_;
 
   IconGroupID group_;
 
   IconSize icon_size_;
 
   scoped_ptr<gfx::Image> image_;
 
   Delegate* delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(IconLoader);
 };
 
 #endif  // CHROME_BROWSER_ICON_LOADER_H_