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

chrome/browser/media_gallery/win/mtp_device_delegate_impl_win.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.
+//
+// MTPDeviceDelegateImplWin implementation.
+
+#include "chrome/browser/media_gallery/win/mtp_device_delegate_impl_win.h"
+
+#include <portabledevice.h>
+#include <vector>
+
+#include "base/file_path.h"
+#include "base/file_util.h"
+#include "base/sequenced_task_runner.h"
+#include "base/string_split.h"
+#include "base/string_util.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "base/utf_string_conversions.h"
+#include "chrome/browser/media_gallery/win/mtp_device_object_entry.h"
+#include "chrome/browser/media_gallery/win/mtp_device_object_enumerator.h"
+#include "chrome/browser/media_gallery/win/mtp_device_operations_util.h"
+#include "chrome/browser/media_gallery/win/recursive_mtp_device_object_enumerator.h"
+#include "chrome/browser/system_monitor/removable_device_notifications_window_win.h"
+#include "chrome/browser/system_monitor/removable_storage_notifications.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace chrome {
+
+namespace {
+
+// Gets the details of the MTP partition storage specified by the
+// |storage_path|. On success, returns true and fills in |pnp_device_id| and
+// |storage_object_id|. On failure, returns false and |pnp_device_id| and
+// |storage_object_id| are not set.
+bool GetStorageInfoFromStoragePath(const string16& storage_path,
+                                   string16* pnp_device_id,
+                                   string16* storage_object_id) {
+  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());

[Peter Kasting, 2012/12/20 21:24:20]

Based on discussion with rsleevi, I suggest two DCHECK changes in this file. 
Both are to make this class agnostic about the actual thread it runs on; given
that the caller supplies a sequenced task runner, there's no reason that runner
couldn't be made to point at a dedicated thread instead of something in the
blocking pool.

So the first change is here.  Let's just remove this DCHECK.  This function is
local to this file so it's reasonable to assume the caller is using it
correctly.  If you were paranoid you could pass in a sequenced task runner and
check that it's running on the current thread (see below), but that seems
unnecessary.

[kmadhusu, 2012/12/21 01:45:23]

Done. Removed the DCHECK.

+  DCHECK(!storage_path.empty());
+  DCHECK(pnp_device_id);
+  DCHECK(storage_object_id);
+  string16 storage_device_id;
+  RemoveChars(storage_path, L"\\\\", &storage_device_id);
+  DCHECK(!storage_device_id.empty());
+  RemovableStorageNotifications* notifications =
+      RemovableStorageNotifications::GetInstance();
+  DCHECK(notifications);
+  return notifications->GetMTPStorageInfoFromDeviceId(
+      UTF16ToUTF8(storage_device_id), pnp_device_id, storage_object_id);
+}
+
+}  // namespace
+
+void CreateMTPDeviceDelegate(const string16& device_location,
+                             base::SequencedTaskRunner* media_task_runner,
+                             const CreateMTPDeviceDelegateCallback& callback) {
+  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());

[Peter Kasting, 2012/12/20 21:24:20]

The second change is here.  Rather than check that the blocking pool runs tasks
on the current thread, just check that |media_task_runner| runs tasks on the
current thread.

[kmadhusu, 2012/12/21 01:45:23]

Done.

+  callback.Run(new MTPDeviceDelegateImplWin(device_location,
+                                            media_task_runner));
+}
+
+// MTPDeviceDelegateImplWin ---------------------------------------------------
+
+MTPDeviceDelegateImplWin::MTPDeviceDelegateImplWin(
+    const string16& fs_root_path,
+    base::SequencedTaskRunner* media_task_runner)
+    : registered_device_path_(fs_root_path),
+      media_task_runner_(media_task_runner),
+      cancel_pending_tasks_(false) {
+  DCHECK(media_task_runner_.get());
+  bool success = GetStorageInfoFromStoragePath(
+      registered_device_path_, &pnp_device_id_, &storage_object_id_);
+  DCHECK(success);
+}
+
+MTPDeviceDelegateImplWin::~MTPDeviceDelegateImplWin() {
+  DCHECK(media_task_runner_->RunsTasksOnCurrentThread());
+}
+
+base::PlatformFileError MTPDeviceDelegateImplWin::GetFileInfo(
+    const FilePath& file_path,
+    base::PlatformFileInfo* file_info) {
+  if (!LazyInit())
+    return base::PLATFORM_FILE_ERROR_FAILED;
+  string16 object_id = GetFileObjectIdFromPath(file_path.value());
+  if (object_id.empty())
+    return base::PLATFORM_FILE_ERROR_FAILED;
+  return MTPDeviceOperationsUtil::GetFileEntryInfo(device_.get(), object_id,
+                                                   file_info);
+}
+
+scoped_ptr<fileapi::FileSystemFileUtil::AbstractFileEnumerator>
+    MTPDeviceDelegateImplWin::CreateFileEnumerator(const FilePath& root,
+                                                   bool recursive) {
+  scoped_ptr<fileapi::FileSystemFileUtil::AbstractFileEnumerator>
+      file_enumerator(new fileapi::FileSystemFileUtil::EmptyFileEnumerator());
+  if (root.value().empty() || !LazyInit())
+    return file_enumerator.Pass();
+
+  string16 object_id = GetFileObjectIdFromPath(root.value());
+  if (object_id.empty())
+    return file_enumerator.Pass();
+
+  MTPDeviceObjectEntries entries;
+  if (!MTPDeviceOperationsUtil::GetDirectoryEntries(device_.get(), object_id,
+                                                    &entries) ||
+      entries.empty())
+    return file_enumerator.Pass();
+
+  if (recursive) {
+    file_enumerator.reset(
+        new RecursiveMTPDeviceObjectEnumerator(device_.get(), entries));
+  } else {
+    file_enumerator.reset(new MTPDeviceObjectEnumerator(entries));
+  }
+  return file_enumerator.Pass();
+}
+
+base::PlatformFileError MTPDeviceDelegateImplWin::CreateSnapshotFile(
+    const FilePath& device_file_path,
+    const FilePath& local_path,
+    base::PlatformFileInfo* file_info) {
+  if (!LazyInit())
+    return base::PLATFORM_FILE_ERROR_FAILED;
+  string16 file_object_id = GetFileObjectIdFromPath(device_file_path.value());
+  if (file_object_id.empty())
+    return base::PLATFORM_FILE_ERROR_FAILED;
+  if (!MTPDeviceOperationsUtil::WriteFileObjectData(device_.get(),
+                                                    file_object_id,
+                                                    local_path))
+    return base::PLATFORM_FILE_ERROR_FAILED;
+  base::PlatformFileError error = GetFileInfo(device_file_path, file_info);
+
+  // LocalFileStreamReader is used to read the contents of the snapshot file.
+  // Snapshot file modification time does not match the last modified time
+  // of the original media file. Therefore, set the last modified time to null
+  // in order to avoid the verification in LocalFileStreamReader.
+  //
+  // Users will use HTML5 FileSystem Entry getMetadata() interface to get actual
+  // last modified time of the media file.
+  file_info->last_modified = base::Time();
+  return error;
+}
+
+base::SequencedTaskRunner* MTPDeviceDelegateImplWin::GetMediaTaskRunner() {
+  return media_task_runner_.get();
+}
+
+void MTPDeviceDelegateImplWin::CancelPendingTasksAndDeleteDelegate() {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  // Caution: This function is called on the UI thread. Access only the thread
+  // safe member variables in this function.

[Peter Kasting, 2012/12/19 20:17:58]

Nit: Given your DCHECK above, this is probably not necessary to spell out... you
can keep it if you think it's critical, though.

[kmadhusu, 2012/12/20 20:37:29]

Removed.

+  {
+    base::AutoLock locked(cancel_tasks_lock_);
+    cancel_pending_tasks_ = true;
+  }
+  media_task_runner_->DeleteSoon(FROM_HERE, this);
+}
+
+bool MTPDeviceDelegateImplWin::LazyInit() {
+  DCHECK(media_task_runner_->RunsTasksOnCurrentThread());
+  {
+    // Device delegate will be destructed soon.

[Peter Kasting, 2012/12/19 20:17:58]

Nit: Perhaps this should instead be:

Both OpenDevice() (which we call below) and any operations our callers do may
take some time.  Abort them immediately if we're in the process of shutting
down.

[kmadhusu, 2012/12/20 20:37:29]

Done.

+    base::AutoLock locked(cancel_tasks_lock_);
+    if (cancel_pending_tasks_)
+      return false;
+  }
+  if (device_.get())
+    return true;  // Already successfully initialized.
+  DCHECK(!pnp_device_id_.empty());
+  return MTPDeviceOperationsUtil::OpenDevice(pnp_device_id_, &device_);
+}
+
+string16 MTPDeviceDelegateImplWin::GetFileObjectIdFromPath(
+    const string16& file_path) {
+  DCHECK(media_task_runner_->RunsTasksOnCurrentThread());
+  DCHECK(!file_path.empty());
+  if (registered_device_path_ == file_path)
+    return storage_object_id_;
+
+  string16 actual_file_path(file_path);
+  ReplaceFirstSubstringAfterOffset(&actual_file_path, 0,
+                                   registered_device_path_, string16());
+  DCHECK(!actual_file_path.empty());
+  typedef std::vector<string16> PathComponents;
+  PathComponents path_components;
+  base::SplitString(actual_file_path, L'\\', &path_components);
+  DCHECK(!path_components.empty());
+  string16 parent_id(storage_object_id_);
+  string16 file_object_id;
+  for (PathComponents::const_iterator path_iter = path_components.begin() + 1;
+       path_iter != path_components.end(); ++path_iter) {
+    file_object_id = MTPDeviceOperationsUtil::GetObjectIdFromName(device_,
+                                                                  parent_id,
+                                                                  *path_iter);
+    if (file_object_id.empty())
+      break;
+    parent_id = file_object_id;
+  }
+  return file_object_id;
+}
+
+}  // namespace chrome