[fsp] Add support for providing thumbnails.

chrome/browser/chromeos/file_system_provider/fake_provided_file_system.cc

 // 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.
 
 #include "chrome/browser/chromeos/file_system_provider/fake_provided_file_system.h"
 
 #include "base/files/file.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "net/base/io_buffer.h"
 
@@ skipping 63 matching lines @@
 }
 
 ProvidedFileSystemInterface::AbortCallback
 FakeProvidedFileSystem::RequestUnmount(
     const storage::AsyncFileUtil::StatusCallback& callback) {
   return PostAbortableTask(base::Bind(callback, base::File::FILE_OK));
 }
 
 ProvidedFileSystemInterface::AbortCallback FakeProvidedFileSystem::GetMetadata(
     const base::FilePath& entry_path,
+    ProvidedFileSystemInterface::MetadataFieldMask fields,
     const ProvidedFileSystemInterface::GetMetadataCallback& callback) {
   const Entries::const_iterator entry_it = entries_.find(entry_path);
 
   if (entry_it == entries_.end()) {
     return PostAbortableTask(base::Bind(
         callback, EntryMetadata(), base::File::FILE_ERROR_NOT_FOUND));
   }
 
   return PostAbortableTask(
       base::Bind(callback, entry_it->second.metadata, base::File::FILE_OK));
@@ skipping 246 matching lines @@
     const std::vector<int>& task_ids,
     const storage::AsyncFileUtil::StatusCallback& callback) {
   for (size_t i = 0; i < task_ids.size(); ++i) {
     tracker_.TryCancel(task_ids[i]);
   }
   callback.Run(base::File::FILE_OK);
 }
 
 }  // namespace file_system_provider
 }  // namespace chromeos