Picasa import: Make NativeMediaFileUtil an AsyncFileUtil

chrome/browser/media_galleries/fileapi/native_media_file_util.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 "chrome/browser/media_galleries/fileapi/native_media_file_util.h"
 
+#include "base/bind.h"
 #include "base/file_util.h"
 #include "base/string_util.h"
-#include "chrome/browser/media_galleries/fileapi/filtering_file_enumerator.h"
+#include "base/task_runner_util.h"
 #include "chrome/browser/media_galleries/fileapi/media_file_system_mount_point_provider.h"
 #include "chrome/browser/media_galleries/fileapi/media_path_filter.h"
 #include "googleurl/src/gurl.h"
 #include "net/base/mime_sniffer.h"
 #include "webkit/browser/fileapi/file_system_context.h"
 #include "webkit/browser/fileapi/file_system_operation_context.h"
 #include "webkit/browser/fileapi/file_system_task_runners.h"
 #include "webkit/browser/fileapi/native_file_util.h"
+#include "webkit/common/blob/shareable_file_reference.h"
 
+using base::Bind;
+using base::Owned;
 using base::PlatformFile;
 using base::PlatformFileError;
 using base::PlatformFileInfo;
+using base::Unretained;
 using fileapi::FileSystemOperationContext;
 using fileapi::FileSystemURL;
 using fileapi::NativeFileUtil;
 
 namespace chrome {
 
 namespace {
 
 // Modelled after ScopedFILEClose.
 struct ScopedPlatformFileClose {
   void operator()(base::PlatformFile* file) {
     if (file && *file != base::kInvalidPlatformFileValue)
       base::ClosePlatformFile(*file);
   }
 };
 
 typedef scoped_ptr<base::PlatformFile, ScopedPlatformFileClose>
     ScopedPlatformFile;
 
+// Used to skip the hidden folders and files. Returns true if the file specified
+// by |path| should be skipped.
+bool ShouldSkip(const base::FilePath& path) {
+  const base::FilePath::StringType base_name = path.BaseName().value();
+  if (base_name.empty())
+    return false;
+
+  // Dot files (aka hidden files)
+  if (base_name[0] == '.')
+    return true;
+
+  // Mac OS X file.
+  if (base_name == FILE_PATH_LITERAL("__MACOSX"))
+    return true;
+
+#if defined(OS_WIN)
+  DWORD file_attributes = ::GetFileAttributes(path.value().c_str());
+  if ((file_attributes != INVALID_FILE_ATTRIBUTES) &&
+      ((file_attributes & FILE_ATTRIBUTE_HIDDEN) != 0))
+    return true;
+#else
+  // Windows always creates a recycle bin folder in the attached device to store
+  // all the deleted contents. On non-windows operating systems, there is no way
+  // to get the hidden attribute of windows recycle bin folders that are present
+  // on the attached device. Therefore, compare the file path name to the
+  // recycle bin name and exclude those folders. For more details, please refer
+  // to http://support.microsoft.com/kb/171694.
+  const char win_98_recycle_bin_name[] = "RECYCLED";
+  const char win_xp_recycle_bin_name[] = "RECYCLER";
+  const char win_vista_recycle_bin_name[] = "$Recycle.bin";
+  if ((base::strncasecmp(base_name.c_str(),
+                         win_98_recycle_bin_name,
+                         strlen(win_98_recycle_bin_name)) == 0) ||
+      (base::strncasecmp(base_name.c_str(),
+                         win_xp_recycle_bin_name,
+                         strlen(win_xp_recycle_bin_name)) == 0) ||
+      (base::strncasecmp(base_name.c_str(),
+                         win_vista_recycle_bin_name,
+                         strlen(win_vista_recycle_bin_name)) == 0))
+    return true;
+#endif
+  return false;
+}
+
 // Returns true if the current thread is capable of doing IO.
 bool IsOnTaskRunnerThread(fileapi::FileSystemOperationContext* context) {
   return context->file_system_context()->task_runners()->
       media_task_runner()->RunsTasksOnCurrentThread();
 }
 
 MediaPathFilter* GetMediaPathFilter(FileSystemOperationContext* context) {
   return context->GetUserValue<MediaPathFilter*>(
           MediaFileSystemMountPointProvider::kMediaPathFilterKey);
 }
 
+void FinishGetFileInfo(
+    const NativeMediaFileUtil::GetFileInfoCallback& callback,
+    PlatformFileInfo* file_info,
+    base::FilePath* platform_path,
+    const PlatformFileError& error) {
+  callback.Run(error, *file_info, *platform_path);
+}
+
+void FinishReadDirectory(
+    const NativeMediaFileUtil::ReadDirectoryCallback& callback,
+    NativeMediaFileUtil::EntryList* file_list,
+    const base::PlatformFileError& error) {
+  callback.Run(error, *file_list, false /* has_more */);
+}
+
+void FinishCreateSnapshotFile(
+    const NativeMediaFileUtil::CreateSnapshotFileCallback& callback,
+    PlatformFileInfo* file_info,
+    base::FilePath* platform_path,
+    scoped_refptr<webkit_blob::ShareableFileReference>* file_ref,
+    PlatformFileError error) {
+  callback.Run(error, *file_info, *platform_path, *file_ref);
+}
+
+void FinishStatusCallback(

[vandebo (ex-Chrome), 2013/05/31 23:22:17]

This isn't needed.

[tommycli, 2013/06/01 01:40:54]

See below.

+    const NativeMediaFileUtil::StatusCallback& callback,
+    PlatformFileError error) {
+  callback.Run(error);
+}
+
 }  // namespace
 
 NativeMediaFileUtil::NativeMediaFileUtil() {
 }
 
-PlatformFileError NativeMediaFileUtil::CreateOrOpen(
+bool NativeMediaFileUtil::CreateOrOpen(
     FileSystemOperationContext* context,
     const FileSystemURL& url,
     int file_flags,
-    PlatformFile* file_handle,
-    bool* created) {
+    const CreateOrOpenCallback& callback) {
   // Only called by NaCl, which should not have access to media file systems.
-  return base::PLATFORM_FILE_ERROR_SECURITY;
-}
-
-PlatformFileError NativeMediaFileUtil::EnsureFileExists(
-    FileSystemOperationContext* context,
-    const FileSystemURL& url, bool* created) {
+  base::PlatformFile invalid_file(base::kInvalidPlatformFileValue);
+  callback.Run(base::PLATFORM_FILE_ERROR_SECURITY,
+               base::PassPlatformFile(&invalid_file),
+               false);
+  return true;
+}
+
+bool NativeMediaFileUtil::EnsureFileExists(
+    FileSystemOperationContext* context,
+    const FileSystemURL& url,
+    const EnsureFileExistsCallback& callback) {
+  callback.Run(base::PLATFORM_FILE_ERROR_SECURITY, false);
+  return true;
+}
+
+bool NativeMediaFileUtil::CreateDirectory(
+    FileSystemOperationContext* context,
+    const FileSystemURL& url,
+    bool exclusive,
+    bool recursive,
+    const StatusCallback& callback) {
+  return base::PostTaskAndReplyWithResult(
+      context->task_runner(),
+      FROM_HERE,
+      Bind(&NativeMediaFileUtil::CreateDirectorySync, Unretained(this),
+           context, url, exclusive, recursive),
+      Bind(&FinishStatusCallback, callback));

[vandebo (ex-Chrome), 2013/05/31 23:22:17]

Just pass callback as the reply callback argument.

[tommycli, 2013/06/01 01:40:54]

I tried to keep all the Sync methods purely synchronous so that Picasa and
Itunes can override them without putting PostTask stuff everywhere.

I think a PostTaskAndReply is not a big price to pay given that it doesn't
involve any ugly memory allocs.

+}
+
+bool NativeMediaFileUtil::GetFileInfo(
+    FileSystemOperationContext* context,
+    const FileSystemURL& url,
+    const GetFileInfoCallback& callback) {
+  PlatformFileInfo* file_info = new PlatformFileInfo();
+  base::FilePath* platform_path = new base::FilePath();
+  return base::PostTaskAndReplyWithResult(

[vandebo (ex-Chrome), 2013/05/31 23:22:17]

This will be cleaner if you just pass the callback down instead of using
PostTaskAndReply.

[tommycli, 2013/06/01 01:40:54]

Done.

+      context->task_runner(),
+      FROM_HERE,
+      Bind(&NativeMediaFileUtil::GetFileInfoSync, Unretained(this),
+           context, url, file_info, platform_path),
+      Bind(&FinishGetFileInfo, callback, Owned(file_info),
+           Owned(platform_path)));
+}
+
+bool NativeMediaFileUtil::ReadDirectory(
+    FileSystemOperationContext* context,
+    const FileSystemURL& url,
+    const ReadDirectoryCallback& callback) {
+  EntryList* entry_list = new EntryList();
+  return base::PostTaskAndReplyWithResult(
+      context->task_runner(),
+      FROM_HERE,
+      Bind(&NativeMediaFileUtil::ReadDirectorySync, Unretained(this),
+           context, url, entry_list),
+      Bind(&FinishReadDirectory, callback, Owned(entry_list)));
+}
+
+bool NativeMediaFileUtil::Touch(
+    FileSystemOperationContext* context,
+    const FileSystemURL& url,
+    const base::Time& last_access_time,
+    const base::Time& last_modified_time,
+    const StatusCallback& callback) {
+  callback.Run(base::PLATFORM_FILE_ERROR_SECURITY);
+  return true;
+}
+
+bool NativeMediaFileUtil::Truncate(
+    FileSystemOperationContext* context,
+    const FileSystemURL& url,
+    int64 length,
+    const StatusCallback& callback) {
+  callback.Run(base::PLATFORM_FILE_ERROR_SECURITY);
+  return true;
+}
+
+bool NativeMediaFileUtil::CopyFileLocal(
+    FileSystemOperationContext* context,
+    const FileSystemURL& src_url,
+    const FileSystemURL& dest_url,
+    const StatusCallback& callback) {
+  return base::PostTaskAndReplyWithResult(
+      context->task_runner(),
+      FROM_HERE,
+      Bind(&NativeMediaFileUtil::CopyOrMoveFileSync, Unretained(this),
+           context, src_url, dest_url, true /* copy */),
+      Bind(&FinishStatusCallback, callback));
+}
+
+bool NativeMediaFileUtil::MoveFileLocal(
+    FileSystemOperationContext* context,
+    const FileSystemURL& src_url,
+    const FileSystemURL& dest_url,
+    const StatusCallback& callback) {
+  return base::PostTaskAndReplyWithResult(
+      context->task_runner(),
+      FROM_HERE,
+      Bind(&NativeMediaFileUtil::CopyOrMoveFileSync, Unretained(this),
+           context, src_url, dest_url, false /* copy */),
+      Bind(&FinishStatusCallback, callback));
+}
+
+bool NativeMediaFileUtil::CopyInForeignFile(
+    FileSystemOperationContext* context,
+    const base::FilePath& src_file_path,
+    const FileSystemURL& dest_url,
+    const StatusCallback& callback) {
+  return base::PostTaskAndReplyWithResult(
+      context->task_runner(),
+      FROM_HERE,
+      Bind(&NativeMediaFileUtil::CopyInForeignFileSync, Unretained(this),
+           context, src_file_path, dest_url),
+      Bind(&FinishStatusCallback, callback));
+}
+
+bool NativeMediaFileUtil::DeleteFile(
+    FileSystemOperationContext* context,
+    const FileSystemURL& url,
+    const StatusCallback& callback) {
+  callback.Run(base::PLATFORM_FILE_ERROR_SECURITY);
+  return true;
+}
+
+bool NativeMediaFileUtil::DeleteDirectory(
+    FileSystemOperationContext* context,
+    const FileSystemURL& url,
+    const StatusCallback& callback) {
+  return base::PostTaskAndReplyWithResult(
+      context->task_runner(),
+      FROM_HERE,
+      Bind(&NativeMediaFileUtil::DeleteDirectorySync, Unretained(this),
+           context, url),
+      Bind(&FinishStatusCallback, callback));
+}
+
+bool NativeMediaFileUtil::CreateSnapshotFile(
+    FileSystemOperationContext* context,
+    const FileSystemURL& url,
+    const CreateSnapshotFileCallback& callback) {
+  PlatformFileInfo* file_info = new PlatformFileInfo();
+  base::FilePath* platform_path = new base::FilePath();
+  scoped_refptr<webkit_blob::ShareableFileReference>* file_ref =
+      new scoped_refptr<webkit_blob::ShareableFileReference>();
+  return base::PostTaskAndReplyWithResult(
+      context->task_runner(),
+      FROM_HERE,
+      Bind(&NativeMediaFileUtil::CreateSnapshotFileSync, Unretained(this),
+           context, url, file_info, platform_path, file_ref),
+      Bind(&FinishCreateSnapshotFile, callback, Owned(file_info),
+           Owned(platform_path), Owned(file_ref)));
+}
+
+PlatformFileError NativeMediaFileUtil::CreateDirectorySync(
+    FileSystemOperationContext* context,
+    const FileSystemURL& url,
+    bool exclusive,
+    bool recursive) {
   base::FilePath file_path;
-  PlatformFileError error = GetFilteredLocalFilePath(context, url, &file_path);
+  PlatformFileError error = GetLocalFilePath(context, url, &file_path);
   if (error != base::PLATFORM_FILE_OK)
     return error;
-  return NativeFileUtil::EnsureFileExists(file_path, created);
-}
-
-scoped_ptr<fileapi::FileSystemFileUtil::AbstractFileEnumerator>
-NativeMediaFileUtil::CreateFileEnumerator(
-    FileSystemOperationContext* context,
-    const FileSystemURL& root_url) {
-  DCHECK(context);
-  return make_scoped_ptr(new FilteringFileEnumerator(
-      IsolatedFileUtil::CreateFileEnumerator(context, root_url),
-      GetMediaPathFilter(context)))
-      .PassAs<FileSystemFileUtil::AbstractFileEnumerator>();
-}
-
-PlatformFileError NativeMediaFileUtil::Touch(
-    FileSystemOperationContext* context,
-    const FileSystemURL& url,
-    const base::Time& last_access_time,
-    const base::Time& last_modified_time) {
-  base::FilePath file_path;
-  PlatformFileError error = GetFilteredLocalFilePathForExistingFileOrDirectory(
-      context,
-      url,
-      // Touch fails for non-existent paths and filtered paths.
-      base::PLATFORM_FILE_ERROR_FAILED,
-      &file_path);
+  return NativeFileUtil::CreateDirectory(file_path, exclusive, recursive);
+}
+
+PlatformFileError NativeMediaFileUtil::GetLocalFilePath(
+    FileSystemOperationContext* context,
+    const FileSystemURL& url,
+    base::FilePath* local_file_path) {
+  DCHECK(local_file_path);
+  DCHECK(url.is_valid());
+  if (url.path().empty()) {
+    // Root direcory case, which should not be accessed.
+    return base::PLATFORM_FILE_ERROR_ACCESS_DENIED;
+  }
+  *local_file_path = url.path();
+  return base::PLATFORM_FILE_OK;
+}
+
+PlatformFileError NativeMediaFileUtil::ReadDirectorySync(
+      FileSystemOperationContext* context,
+      const FileSystemURL& url,
+      EntryList* file_list) {
+  DCHECK(file_list);
+  DCHECK(file_list->empty());
+  base::PlatformFileInfo file_info;
+  base::FilePath platform_path;
+  PlatformFileError error = GetFileInfoSync(context, url, &file_info,
+                                            &platform_path);
+
+  if (error == base::PLATFORM_FILE_OK && !file_info.is_directory)
+    return base::PLATFORM_FILE_ERROR_NOT_A_DIRECTORY;
+
   if (error != base::PLATFORM_FILE_OK)
     return error;
-  return NativeFileUtil::Touch(file_path, last_access_time, last_modified_time);
-}
-
-PlatformFileError NativeMediaFileUtil::Truncate(
-    FileSystemOperationContext* context,
-    const FileSystemURL& url,
-    int64 length) {
-  base::FilePath file_path;
-  PlatformFileError error = GetFilteredLocalFilePathForExistingFileOrDirectory(
-      context,
-      url,
-      // Cannot truncate paths that do not exist, or are filtered.
-      base::PLATFORM_FILE_ERROR_NOT_FOUND,
-      &file_path);
-  if (error != base::PLATFORM_FILE_OK)
-    return error;
-  return NativeFileUtil::Truncate(file_path, length);
-}
-
-PlatformFileError NativeMediaFileUtil::CopyOrMoveFile(
+
+  file_util::FileEnumerator file_enum(
+      platform_path,
+      false /* recursive */,
+      file_util::FileEnumerator::FILES |
+          file_util::FileEnumerator::DIRECTORIES);
+  file_util::FileEnumerator::FindInfo file_util_info;
+#if defined(OS_WIN)
+  memset(&file_util_info, 0, sizeof(file_util_info));
+#endif  // defined(OS_WIN)
+
+  for (base::FilePath platform_path = file_enum.Next();
+       !platform_path.empty();
+       platform_path = file_enum.Next()) {
+    // Skip symlinks.
+    if (file_util::IsLink(platform_path))
+      continue;
+
+    file_enum.GetFindInfo(&file_util_info);
+
+    // NativeMediaFileUtil skip criteria.
+    if (ShouldSkip(platform_path))
+      continue;
+    if (!file_util::FileEnumerator::IsDirectory(file_util_info) &&
+        !GetMediaPathFilter(context)->Match(platform_path))
+      continue;
+
+    fileapi::DirectoryEntry entry;
+    entry.is_directory = file_util::FileEnumerator::IsDirectory(file_util_info);
+    entry.name = platform_path.BaseName().value();
+    entry.size = file_util::FileEnumerator::GetFilesize(file_util_info);
+    entry.last_modified_time =
+        file_util::FileEnumerator::GetLastModifiedTime(file_util_info);
+
+    file_list->push_back(entry);
+  }
+
+  return base::PLATFORM_FILE_OK;
+}
+
+PlatformFileError NativeMediaFileUtil::CopyOrMoveFileSync(
     FileSystemOperationContext* context,
     const FileSystemURL& src_url,
     const FileSystemURL& dest_url,
     bool copy) {
   base::FilePath src_file_path;
   PlatformFileError error =
       GetFilteredLocalFilePathForExistingFileOrDirectory(
           context, src_url,
           base::PLATFORM_FILE_ERROR_NOT_FOUND,
           &src_file_path);
@@ skipping 12 matching lines @@
       error != base::PLATFORM_FILE_ERROR_NOT_FOUND)
     return error;
   if (error == base::PLATFORM_FILE_OK && file_info.is_directory)
     return base::PLATFORM_FILE_ERROR_INVALID_OPERATION;
   if (!GetMediaPathFilter(context)->Match(dest_file_path))
     return base::PLATFORM_FILE_ERROR_SECURITY;
 
   return NativeFileUtil::CopyOrMoveFile(src_file_path, dest_file_path, copy);
 }
 
-PlatformFileError NativeMediaFileUtil::CopyInForeignFile(
+PlatformFileError NativeMediaFileUtil::CopyInForeignFileSync(
     FileSystemOperationContext* context,
     const base::FilePath& src_file_path,
     const FileSystemURL& dest_url) {
   if (src_file_path.empty())
     return base::PLATFORM_FILE_ERROR_INVALID_OPERATION;
 
   base::FilePath dest_file_path;
   PlatformFileError error =
       GetFilteredLocalFilePath(context, dest_url, &dest_file_path);
   if (error != base::PLATFORM_FILE_OK)
     return error;
   return NativeFileUtil::CopyOrMoveFile(src_file_path, dest_file_path, true);
 }
 
-PlatformFileError NativeMediaFileUtil::DeleteFile(
+PlatformFileError NativeMediaFileUtil::GetFilteredLocalFilePath(
     FileSystemOperationContext* context,
-    const FileSystemURL& url) {
+    const FileSystemURL& file_system_url,
+    base::FilePath* local_file_path) {
   base::FilePath file_path;
-  PlatformFileError error = GetLocalFilePath(context, url, &file_path);
+  PlatformFileError error =
+      GetLocalFilePath(context, file_system_url, &file_path);
   if (error != base::PLATFORM_FILE_OK)
     return error;
-  PlatformFileInfo file_info;
-  error = NativeFileUtil::GetFileInfo(file_path, &file_info);
-  if (error != base::PLATFORM_FILE_OK)
-    return error;
-  if (file_info.is_directory)
-    return base::PLATFORM_FILE_ERROR_NOT_A_FILE;
   if (!GetMediaPathFilter(context)->Match(file_path))
-    return base::PLATFORM_FILE_ERROR_NOT_FOUND;
-  return NativeFileUtil::DeleteFile(file_path);
+    return base::PLATFORM_FILE_ERROR_SECURITY;
+
+  *local_file_path = file_path;
+  return base::PLATFORM_FILE_OK;
 }
 
-PlatformFileError NativeMediaFileUtil::GetFileInfo(
+PlatformFileError NativeMediaFileUtil::GetFileInfoSync(
     FileSystemOperationContext* context,
     const FileSystemURL& url,
     PlatformFileInfo* file_info,
     base::FilePath* platform_path) {
   DCHECK(context);
-  DCHECK(GetMediaPathFilter(context));
   DCHECK(file_info);
   DCHECK(platform_path);
+  DCHECK(GetMediaPathFilter(context));
 
-  base::PlatformFileError error =
-      IsolatedFileUtil::GetFileInfo(context, url, file_info, platform_path);
+  base::FilePath file_path;
+  PlatformFileError error = GetLocalFilePath(context, url, &file_path);
+  if (error != base::PLATFORM_FILE_OK)
+    return error;
+  if (file_util::IsLink(file_path))
+    return base::PLATFORM_FILE_ERROR_NOT_FOUND;
+  error = NativeFileUtil::GetFileInfo(file_path, file_info);
   if (error != base::PLATFORM_FILE_OK)
     return error;
 
+  *platform_path = file_path;

[vandebo (ex-Chrome), 2013/05/31 23:22:17]

if (platform_path) and don't pass platform_path if you don't need it. (I think
there's someplace where this is the case.)

[tommycli, 2013/06/01 01:40:54]

Done.

   if (file_info->is_directory ||
       GetMediaPathFilter(context)->Match(*platform_path)) {
     return base::PLATFORM_FILE_OK;
   }
   return base::PLATFORM_FILE_ERROR_NOT_FOUND;
 }
 
-PlatformFileError NativeMediaFileUtil::GetFilteredLocalFilePath(
-    FileSystemOperationContext* context,
-    const FileSystemURL& file_system_url,
-    base::FilePath* local_file_path) {
-  base::FilePath file_path;
-  PlatformFileError error =
-      IsolatedFileUtil::GetLocalFilePath(context, file_system_url, &file_path);
-  if (error != base::PLATFORM_FILE_OK)
-    return error;
-  if (!GetMediaPathFilter(context)->Match(file_path))
-    return base::PLATFORM_FILE_ERROR_SECURITY;
-
-  *local_file_path = file_path;
-  return base::PLATFORM_FILE_OK;
-}
-
 PlatformFileError
 NativeMediaFileUtil::GetFilteredLocalFilePathForExistingFileOrDirectory(
     FileSystemOperationContext* context,
     const FileSystemURL& file_system_url,
     PlatformFileError failure_error,
     base::FilePath* local_file_path) {
   base::FilePath file_path;
   PlatformFileError error =
       GetLocalFilePath(context, file_system_url, &file_path);
   if (error != base::PLATFORM_FILE_OK)
     return error;
 
   if (!file_util::PathExists(file_path))
     return failure_error;
   PlatformFileInfo file_info;
   if (!file_util::GetFileInfo(file_path, &file_info))
     return base::PLATFORM_FILE_ERROR_FAILED;
 
   if (!file_info.is_directory &&
       !GetMediaPathFilter(context)->Match(file_path)) {
     return failure_error;
   }
 
   *local_file_path = file_path;
   return base::PLATFORM_FILE_OK;
 }
 
-webkit_blob::ScopedFile NativeMediaFileUtil::CreateSnapshotFile(
-    fileapi::FileSystemOperationContext* context,
+PlatformFileError NativeMediaFileUtil::DeleteDirectorySync(
+    FileSystemOperationContext* context,
+    const FileSystemURL& url) {
+  base::FilePath file_path;
+  PlatformFileError error = GetLocalFilePath(context, url, &file_path);
+  if (error != base::PLATFORM_FILE_OK)
+    return error;
+  return NativeFileUtil::DeleteDirectory(file_path);
+}
+
+PlatformFileError NativeMediaFileUtil::CreateSnapshotFileSync(
+    FileSystemOperationContext* context,
     const fileapi::FileSystemURL& url,
-    base::PlatformFileError* error,
-    base::PlatformFileInfo* file_info,
-    base::FilePath* platform_path) {
-  DCHECK(IsOnTaskRunnerThread(context));
-  webkit_blob::ScopedFile file;
-  file = IsolatedFileUtil::CreateSnapshotFile(
-      context, url, error, file_info, platform_path);
-  if (*error != base::PLATFORM_FILE_OK)
-    return file.Pass();
-  *error = IsMediaFile(*platform_path);
-  if (*error == base::PLATFORM_FILE_OK)
-    return file.Pass();
-  return webkit_blob::ScopedFile();
+    PlatformFileInfo* file_info,
+    base::FilePath* platform_path,
+    scoped_refptr<webkit_blob::ShareableFileReference>* file_ref) {
+  PlatformFileError error =
+      GetFileInfoSync(context, url, file_info, platform_path);
+  if (error == base::PLATFORM_FILE_OK && file_info->is_directory)
+    error = base::PLATFORM_FILE_ERROR_NOT_A_FILE;
+  if (error == base::PLATFORM_FILE_OK)
+    error = NativeMediaFileUtil::IsMediaFile(*platform_path);
+
+  // We're just returning the local file information.
+  *file_ref = scoped_refptr<webkit_blob::ShareableFileReference>();
+
+  return error;
 }
 
 // static
-base::PlatformFileError NativeMediaFileUtil::IsMediaFile(
+PlatformFileError NativeMediaFileUtil::IsMediaFile(
     const base::FilePath& path) {
   base::PlatformFile file_handle;
   const int flags = base::PLATFORM_FILE_OPEN | base::PLATFORM_FILE_READ;
-  base::PlatformFileError error =
+  PlatformFileError error =
       NativeFileUtil::CreateOrOpen(path, flags, &file_handle, NULL);
   if (error != base::PLATFORM_FILE_OK)
     return error;
 
   ScopedPlatformFile scoped_platform_file(&file_handle);
   char buffer[net::kMaxBytesToSniff];
 
   // Read as much as net::SniffMimeTypeFromLocalData() will bother looking at.
   int64 len =
       base::ReadPlatformFile(file_handle, 0, buffer, net::kMaxBytesToSniff);
   if (len < 0)
     return base::PLATFORM_FILE_ERROR_FAILED;
   if (len == 0)
     return base::PLATFORM_FILE_ERROR_SECURITY;
 
   std::string mime_type;
   if (!net::SniffMimeTypeFromLocalData(buffer, len, &mime_type))
     return base::PLATFORM_FILE_ERROR_SECURITY;
 
   if (StartsWithASCII(mime_type, "image/", true) ||
       StartsWithASCII(mime_type, "audio/", true) ||
       StartsWithASCII(mime_type, "video/", true) ||
       mime_type == "application/x-shockwave-flash") {
     return base::PLATFORM_FILE_OK;
   }
   return base::PLATFORM_FILE_ERROR_SECURITY;
 }
 
 }  // namespace chrome