Crash fix in fileapi::FileSystemOperation::DidGetUsageAndQuotaAndRunTask

https://chromiumcodereview.appspot.com/10008047 introduced delete-with-inflight-tasks in Write sequence but I failed to convert this callback to use WeakPtr().

BUG=128178
TEST=manual test

Review URL: https://chromiumcodereview.appspot.com/10408006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@137635 0039d316-1c4b-4281-b951-d872f2087c98
void FileSystemOperation::Move(const GURL& src_path_url,
                               const GURL& dest_path_url,
                               const StatusCallback& callback) {
  DCHECK(SetPendingOperationType(kOperationMove));

  base::PlatformFileError result = SetUpFileSystemPath(
      src_path_url, &src_path_, &src_util_, PATH_FOR_WRITE);
  if (result == base::PLATFORM_FILE_OK)
    result = SetUpFileSystemPath(
        dest_path_url, &dest_path_, &dest_util_, PATH_FOR_CREATE);
  if (result != base::PLATFORM_FILE_OK) {
    callback.Run(result);
    delete this;
    return;
  }

  GetUsageAndQuotaThenRunTask(
      dest_path_.origin(), dest_path_.type(),
      base::Bind(&FileSystemOperation::DoMove,
                 base::Unretained(this), callback),
      base::Bind(callback, base::PLATFORM_FILE_ERROR_FAILED));
}

void FileSystemOperation::Move(const GURL& src_path_url,
                               const GURL& dest_path_url,
                               const StatusCallback& callback) {
  DCHECK(SetPendingOperationType(kOperationMove));

  base::PlatformFileError result = SetUpFileSystemPath(
      src_path_url, &src_path_, &src_util_, PATH_FOR_WRITE);
  if (result == base::PLATFORM_FILE_OK)
    result = SetUpFileSystemPath(
        dest_path_url, &dest_path_, &dest_util_, PATH_FOR_CREATE);
  if (result != base::PLATFORM_FILE_OK) {
    callback.Run(result);
    delete this;
    return;
  }

  GetUsageAndQuotaThenRunTask(
      dest_path_.origin(), dest_path_.type(),
      base::Bind(&FileSystemOperation::DoMove,
                 base::Unretained(this), callback),
      base::Bind(callback, base::PLATFORM_FILE_ERROR_FAILED));
}
