[fsp] Add support for providing thumbnails.

chrome/browser/chromeos/file_system_provider/provided_file_system.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_H_
 #define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_H_
 
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/chromeos/file_system_provider/provided_file_system_info.h"
 #include "chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h"
@@ skipping 25 matching lines @@
  public:
   ProvidedFileSystem(Profile* profile,
                      const ProvidedFileSystemInfo& file_system_info);
   virtual ~ProvidedFileSystem();
 
   // ProvidedFileSystemInterface overrides.
   virtual AbortCallback RequestUnmount(
       const storage::AsyncFileUtil::StatusCallback& callback) OVERRIDE;
   virtual AbortCallback GetMetadata(
       const base::FilePath& entry_path,
+      MetadataFieldMask fields,
       const GetMetadataCallback& callback) OVERRIDE;
   virtual AbortCallback ReadDirectory(
       const base::FilePath& directory_path,
       const storage::AsyncFileUtil::ReadDirectoryCallback& callback) OVERRIDE;
   virtual AbortCallback OpenFile(const base::FilePath& file_path,
                                  OpenFileMode mode,
                                  const OpenFileCallback& callback) OVERRIDE;
   virtual AbortCallback CloseFile(
       int file_handle,
       const storage::AsyncFileUtil::StatusCallback& callback) OVERRIDE;
@@ skipping 51 matching lines @@
   RequestManager request_manager_;
 
   base::WeakPtrFactory<ProvidedFileSystem> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(ProvidedFileSystem);
 };
 
 }  // namespace file_system_provider
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_H_