Change DCHECKs to CHECKs to investigate a crash when aborting in Files app.

chrome/browser/chromeos/file_system_provider/throttled_file_system.cc

 // Copyright 2015 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/chromeos/file_system_provider/throttled_file_system.h"
 
 #include <limits>
 #include <vector>
 
 #include "base/files/file.h"
@@ skipping 198 matching lines @@
 }
 
 void ThrottledFileSystem::OnCloseFileCompleted(
     int file_handle,
     const storage::AsyncFileUtil::StatusCallback& callback,
     base::File::Error result) {
   // Closing is always final. Even if an error happened, the file is considered
   // closed on the C++ side. Release the task from the queue, so other files
   // which are enqueued can be opened.
   const auto it = opened_files_.find(file_handle);
-  DCHECK(it != opened_files_.end());
+  CHECK(it != opened_files_.end());
 
   const int queue_token = it->second;
   open_queue_->Remove(queue_token);
   opened_files_.erase(file_handle);
 
   callback.Run(result);
 }
 
 }  // namespace file_system_provider
 }  // namespace chromeos