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

chrome/browser/icon_loader.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 "base/basictypes.h"
 #include "base/bind.h"
 #include "content/public/browser/browser_thread.h"
 
@@ skipping 18 matching lines @@
       base::Bind(&IconLoader::OnReadGroup, this));
 }
 
 void IconLoader::ReadGroup() {
   group_ = ReadGroupIDFromFilepath(file_path_);
 }
 
 void IconLoader::OnReadGroup() {
   if (IsIconMutableFromFilepath(file_path_) ||
       !delegate_->OnGroupLoaded(this, group_)) {
-    BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
+    BrowserThread::PostTask(ReadIconThreadID(), FROM_HERE,
         base::Bind(&IconLoader::ReadIcon, this));
   }
 }
 
 void IconLoader::NotifyDelegate() {
   // If the delegate takes ownership of the Image, release it from the scoped
   // pointer.
   if (delegate_->OnImageLoaded(this, image_.get(), group_))
     ignore_result(image_.release());  // Can't ignore return value.
 }