[fsp] Allow to create multiple observers for a directory, up to one per origin.

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 305 matching lines @@
     entry->contents.resize(entry->metadata->size);
   }
 
   entry->contents.replace(offset, length, buffer->data(), length);
 
   return PostAbortableTask(base::Bind(callback, base::File::FILE_OK));
 }
 
 ProvidedFileSystemInterface::AbortCallback
 FakeProvidedFileSystem::ObserveDirectory(
+    const GURL& origin,
     const base::FilePath& directory_path,
     bool recursive,
+    bool persistent,
     const storage::AsyncFileUtil::StatusCallback& callback) {
   // TODO(mtomasz): Implement it once needed.
   return PostAbortableTask(base::Bind(callback, base::File::FILE_OK));
 }
 
 void FakeProvidedFileSystem::UnobserveEntry(
+    const GURL& origin,
     const base::FilePath& entry_path,
     const storage::AsyncFileUtil::StatusCallback& callback) {
   // TODO(mtomasz): Implement it once needed.
   callback.Run(base::File::FILE_OK);
 }
 
 const ProvidedFileSystemInfo& FakeProvidedFileSystem::GetFileSystemInfo()
     const {
   return file_system_info_;
 }
@@ skipping 57 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