drive: Fix DriveFileStreamReader to run cancel closure on the right thread

chrome/browser/chromeos/drive/drive_file_stream_reader.cc

 // Copyright 2013 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/drive/drive_file_stream_reader.h"
 
 #include <algorithm>
 #include <cstring>
 
 #include "base/callback_helpers.h"
@@ skipping 342 matching lines @@
   }
   DCHECK(entry);
 
   net::HttpByteRange byte_range = in_byte_range;
   if (!byte_range.ComputeBounds(entry->file_info().size())) {
     // If |byte_range| is invalid (e.g. out of bounds), return with an error.
     // At the same time, we cancel the in-flight downloading operation if
     // needed and and invalidate weak pointers so that we won't
     // receive unwanted callbacks.
     if (!ui_cancel_download_closure.is_null())
-      ui_cancel_download_closure.Run();
+      RunTaskOnUIThread(ui_cancel_download_closure);
     weak_ptr_factory_.InvalidateWeakPtrs();
     callback.Run(
         net::ERR_REQUEST_RANGE_NOT_SATISFIABLE, scoped_ptr<ResourceEntry>());
     return;
   }
 
   // Note: both boundary of |byte_range| are inclusive.
   int64 range_length =
       byte_range.last_byte_position() - byte_range.first_byte_position() + 1;
   DCHECK_GE(range_length, 0);
@@ skipping 68 matching lines @@
     // Note: due to the same reason, LocalReaderProxy::OnCompleted may
     // or may not be called. This is timing issue, and it is difficult to avoid
     // unfortunately.
     if (error != FILE_ERROR_OK) {
       callback.Run(FileErrorToNetError(error), scoped_ptr<ResourceEntry>());
     }
   }
 }
 
 }  // namespace drive