[Media Galleries] Switch Mac MTP delegate to async interface.

webkit/fileapi/media/mtp_device_async_delegate.h

 // Copyright (c) 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.
 
 #ifndef WEBKIT_FILEAPI_MEDIA_MTP_DEVICE_ASYNC_DELEGATE_H_
 #define WEBKIT_FILEAPI_MEDIA_MTP_DEVICE_ASYNC_DELEGATE_H_
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/platform_file.h"
 #include "webkit/fileapi/async_file_util.h"
 
 namespace base {
 class FilePath;
 }
 
 namespace fileapi {
 
 // Asynchronous delegate for media transfer protocol (MTP) device to perform
 // media device isolated file system operations. Class that implements this
 // delegate does the actual communication with the MTP device.
 // ScopedMTPDeviceMapEntry class manages the lifetime of the delegate via
 // MTPDeviceMapService class. Member functions and callbacks runs on the IO
 // thread.
+// Note: caller must ensure that the deleting call is not made while there are

[Lei Zhang, 2013/03/18 09:25:55]

I don't think the caller to CancelPendingTasksAndDeleteDelegate() ensures this
condition.

Can't you just run all the error callbacks in |read_dir_transactions_| and
|read_file_transactions_| when we are deleting the delegate?

[Greg Billock, 2013/03/20 23:43:55]

Uggh. I wasn't sure about this. OK, I'll switch it up.

On 2013/03/18 09:25:55, Lei Zhang wrote:

+// outstanding async calls to the delegate.
 class MTPDeviceAsyncDelegate {
  public:
   // A callback to be called when GetFileInfo method call succeeds.
   typedef base::Callback<
       void(const base::PlatformFileInfo& file_info)> GetFileInfoSuccessCallback;
 
   // A callback to be called when ReadDirectory method call succeeds.
   typedef base::Callback<
       void(const AsyncFileUtil::EntryList& file_list,
            bool has_more)> ReadDirectorySuccessCallback;
@@ skipping 41 matching lines @@
   virtual void CancelPendingTasksAndDeleteDelegate() = 0;
 
  protected:
   // Always destruct this object via CancelPendingTasksAndDeleteDelegate().
   virtual ~MTPDeviceAsyncDelegate() {}
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_MEDIA_MTP_DEVICE_ASYNC_DELEGATE_H_