Cleanup: Remove unneeded browser_thread.h includes in contents.

chrome/browser/ui/cocoa/download/download_item_mac.mm

 // 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/ui/cocoa/download/download_item_mac.h"
 
+#include "base/bind.h"
 #include "base/callback.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/download/download_item_model.h"
 #import "chrome/browser/ui/cocoa/download/download_item_controller.h"
 #include "content/public/browser/download_item.h"
 #include "ui/gfx/image/image.h"
 
 using content::DownloadItem;
 
 // DownloadItemMac -------------------------------------------------------------
@@ skipping 76 matching lines @@
                          base::Bind(&DownloadItemMac::OnExtractIconComplete,
                                     base::Unretained(this)),
                          &cancelable_task_tracker_);
 }
 
 void DownloadItemMac::OnExtractIconComplete(gfx::Image* icon) {
   if (!icon)
     return;
   [item_controller_ setIcon:icon->ToNSImage()];
 }