[Media Gallery] Added code to support mtp device media file system on Windows.

chrome/browser/media_gallery/win/mtp_device_operations_util.h

+// 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.
+
+// MTPDeviceOperationsUtil provides support to media filesystem operations.
+// It has several utility functions to open a media transfer protocol (MTP)
+// device for communication, to enumerate the device contents, to read the
+// device file object, etc. All these tasks may take an arbitary long time
+// to complete. This class segregates those functionalities and runs them
+// in the blocking pool thread rather than in the UI thread.
+
+#ifndef CHROME_BROWSER_MEDIA_GALLERY_WIN_MTP_DEVICE_OPERATIONS_UTIL_H_
+#define CHROME_BROWSER_MEDIA_GALLERY_WIN_MTP_DEVICE_OPERATIONS_UTIL_H_
+
+#include <portabledeviceapi.h>
+
+#include <string>
+
+#include "base/string16.h"
+#include "base/platform_file.h"

[Lei Zhang, 2012/11/01 02:34:57]

move up 1 line

[kmadhusu, 2012/11/01 17:59:00]

Done.

+#include "base/win/scoped_comptr.h"
+#include "chrome/browser/media_gallery/win/mtp_device_object_entry.h"
+
+namespace chrome {
+
+// See the top of the file for complete class description.
+class MTPDeviceOperationsUtil {
+ public:
+  // Opens the device for communication. |pnp_device_id| specifies the plug and
+  // play device ID string. On success, returns true and updates |device| with
+  // the portable device interface.
+  static bool OpenDevice(const string16& pnp_device_id,

[kmadhusu, 2012/11/01 01:17:24]

I can reuse this function in portable_device_watcher_win.cc. I will make those
changes in a separate CL.

+                         base::win::ScopedComPtr<IPortableDevice>* device);
+
+  // Gets the details of the object specified by |object_id| from the given MTP
+  // |device|. On success, fills in |file_entry_info|. On failure, returns the
+  // corresponding platform file error and |file_entry_info| is not set.
+  static base::PlatformFileError GetFileEntryInfo(
+      IPortableDevice* device,
+      const string16& object_id,
+      base::PlatformFileInfo* file_entry_info);
+
+  // Gets the entries of the directory specified by |directory_object_id| from
+  // the given MTP |device|. On success, returns true and fills in
+  // |object_entries|. On failure, returns false and |object_entries| are not
+  // set.
+  static bool GetDirectoryEntries(IPortableDevice* device,
+                                  const string16& directory_object_id,
+                                  MTPDeviceObjectEntries* object_entries);
+
+  // Gets the data of the object specified by |file_object_id| from the given
+  // MTP |device|. On success, returns true and fills in |file_data|. On
+  // failure, returns false and |file_data| is not set.
+  static bool GetFileObjectData(IPortableDevice* device,
+                                const string16& file_object_id,
+                                std::string* file_data);
+
+  // Returns the identifier of the object specified by the |object_name|.
+  // |parent_id| specifies the object's parent identifier.
+  static string16 GetObjectIdFromName(IPortableDevice* device,
+                                      const string16& parent_id,
+                                      const string16& object_name);
+
+ private:
+  // All methods are static, this class should not be instantiated.
+  MTPDeviceOperationsUtil();
+
+  // Helper to create a MTP device object entry for the given |device|
+  // and |object_id|. On success, returns true and fills in |entry|. On
+  // failure, returns false and |entry| is not set.
+  static bool GetMTPDeviceObjectEntry(IPortableDevice* device,

[Lei Zhang, 2012/11/01 02:34:57]

Can this go in the .cc file's anonymous namespace instead?

[kmadhusu, 2012/11/01 17:59:00]

Done.

+                                      const string16& object_id,
+                                      MTPDeviceObjectEntry* entry);
+
+  DISALLOW_COPY_AND_ASSIGN(MTPDeviceOperationsUtil);
+};
+
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_MEDIA_GALLERY_WIN_MTP_DEVICE_OPERATIONS_UTIL_H_