URLFetcher won't call delegate until file is closed.

net/base/file_stream.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 "net/base/file_stream.h"
 
 #include "base/location.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/task_runner_util.h"
 #include "base/threading/thread_restrictions.h"
@@ skipping 75 matching lines @@
   if (IsOpen()) {
     DLOG(FATAL) << "File is already open!";
     return ERR_UNEXPECTED;
   }
 
   open_flags_ = open_flags;
   DCHECK(!is_async());
   return context_->OpenSync(path, open_flags_);
 }
 
+int FileStream::Close(const CompletionCallback& callback) {
+  if (!is_async()) {
+    context_->CloseSync();
+    context_.reset();
+    return OK;
+  }
+  context_->CloseAsync(callback);
+  return ERR_IO_PENDING;
+}
+
 bool FileStream::IsOpen() const {
   return context_->file() != base::kInvalidPlatformFileValue;
 }
 
 int FileStream::Seek(Whence whence,
                      int64 offset,
                      const Int64CompletionCallback& callback) {
   if (!IsOpen())
     return ERR_UNEXPECTED;
 
@@ skipping 170 matching lines @@
 
   owner_bound_net_log.AddEvent(NetLog::TYPE_FILE_STREAM_SOURCE,
       bound_net_log_.source().ToEventParametersCallback());
 }
 
 base::PlatformFile FileStream::GetPlatformFileForTesting() {
   return context_->file();
 }
 
 }  // namespace net