[fsp] Add throttling for number of opened files.

chrome/browser/chromeos/file_system_provider/provided_file_system_info.h

 // Copyright 2014 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 CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_INFO_H_
 #define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_INFO_H_
 
 #include <string>
 
 #include "base/files/file_path.h"
 
 namespace chromeos {
 namespace file_system_provider {
 
 // Options for creating the provided file system info.
 struct MountOptions {
   MountOptions();
 
   // Only mandatory fields.
   MountOptions(const std::string& file_system_id,
                const std::string& display_name);
 
   std::string file_system_id;
   std::string display_name;
   bool writable;
   bool supports_notify_tag;
+  int opened_files_limit;
 };
 
 // Contains information about the provided file system instance.
 class ProvidedFileSystemInfo {
  public:
   ProvidedFileSystemInfo();
 
   ProvidedFileSystemInfo(const std::string& extension_id,
                          const MountOptions& mount_options,
                          const base::FilePath& mount_path);
 
   ~ProvidedFileSystemInfo();
 
   const std::string& extension_id() const { return extension_id_; }
   const std::string& file_system_id() const { return file_system_id_; }
   const std::string& display_name() const { return display_name_; }
   bool writable() const { return writable_; }
   bool supports_notify_tag() const { return supports_notify_tag_; }
+  int opened_files_limit() const { return opened_files_limit_; }
   const base::FilePath& mount_path() const { return mount_path_; }
 
  private:
   // ID of the extension providing this file system.
   std::string extension_id_;
 
   // ID of the file system.
   std::string file_system_id_;
 
   // Name of the file system, can be rendered in the UI.
   std::string display_name_;
 
   // Whether the file system is writable or just read-only.
   bool writable_;
 
   // Supports tags for file/directory change notifications.
   bool supports_notify_tag_;
 
+  // Limit of opened files in parallel. If unlimited, then 0.
+  int opened_files_limit_;
+
   // Mount path of the underlying file system.
   base::FilePath mount_path_;
 };
 
 }  // namespace file_system_provider
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_INFO_H_