Subject .mm files to the header sorting presubmit

ios/chrome/browser/snapshots/snapshot_cache.mm

 // Copyright 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.
 
 #import "ios/chrome/browser/snapshots/snapshot_cache.h"
 
 #import <UIKit/UIKit.h>
 
 #include "base/critical_closure.h"
-#include "base/mac/bind_objc_block.h"
 #include "base/files/file_enumerator.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/mac/bind_objc_block.h"
+#include "base/mac/bind_objc_block.h"

[tapted, 2015/05/19 03:31:10]

heh. I guess I can delete this one. aaaand a few others.

 #include "base/mac/scoped_cftyperef.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/task_runner_util.h"
 #include "base/threading/thread_restrictions.h"
 #include "ios/chrome/browser/ui/ui_util.h"
 #import "ios/chrome/browser/ui/uikit_ui_util.h"
 #include "ios/web/public/web_thread.h"
 
 @interface SnapshotCache ()
 + (base::FilePath)imagePathForSessionID:(NSString*)sessionID;
@@ skipping 473 matching lines @@
       backgroundingImageSessionId_.reset();
     }
   }
 
   web::WebThread::PostBlockingPoolTask(
       FROM_HERE, base::Bind(&ConvertAndSaveGreyImage, colorImagePath,
                             greyImagePath, backgroundingColorImage_));
 }
 
 @end