[fsp] Add requestUnmount() method together with the request manager.

chrome/browser/chromeos/file_system_provider/request_manager.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_REQUEST_MANAGER_H_
+#define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_REQUEST_MANAGER_H_
+
+#include <map>
+#include <string>
+
+#include "base/callback.h"
+#include "base/files/file.h"
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/chromeos/file_system_provider/observer.h"
+#include "chrome/browser/chromeos/file_system_provider/provided_file_system.h"
+
+namespace base {
+class DictionaryValue;
+}  // namespace base
+
+namespace chromeos {
+namespace file_system_provider {
+
+typedef base::Callback<void(scoped_ptr<base::DictionaryValue>, bool has_next)>
+    SuccessCallback;
+typedef base::Callback<void(base::File::Error)> ErrorCallback;
+
+// Manages requests between the service, async utils and the providing
+// extensions.
+class RequestManager : public Observer {
+ public:
+  RequestManager();
+  virtual ~RequestManager();
+
+  // Creates a request and returns its request id (greater than 0). Returns 0 in
+  // case of an error (eg. too many requests). The passed callbacks can be NULL.
+  int CreateRequest(const ProvidedFileSystem& file_system,
+                    const SuccessCallback& success_callback,
+                    const ErrorCallback& error_callback);
+
+  // Handles successful response for the |request_id|. If |has_next| is false,
+  // then the request is disposed, after handling the |response|. On error,
+  // returns false, and the request is disposed.
+  bool FulfillRequest(const ProvidedFileSystem& file_system,
+                      int request_id,
+                      scoped_ptr<base::DictionaryValue> response,
+                      bool has_next);
+
+  // Handles error response for the |request_id|. If handling the error fails,
+  // returns false. Always disposes the request.
+  bool RejectRequest(const ProvidedFileSystem& file_system,
+                     int request_id,
+                     base::File::Error error);
+
+  // file_system_provider::Observer overrides.
+  virtual void OnProvidedFileSystemMount(const ProvidedFileSystem& file_system,
+                                         base::File::Error error) OVERRIDE;
+  virtual void OnProvidedFileSystemUnmount(
+      const ProvidedFileSystem& file_system,
+      base::File::Error error) OVERRIDE;
+
+ private:
+  struct Request {
+    Request();
+    ~Request();
+
+    // Provided file system handling the request.
+    ProvidedFileSystem file_system;
+
+    // Callback to be called on success.
+    SuccessCallback success_callback;
+
+    // Callback to be called on error.
+    ErrorCallback error_callback;
+  };
+
+  typedef std::map<int, Request> RequestMap;
+
+  RequestMap requests_;
+  int next_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(RequestManager);
+};
+
+}  // namespace file_system_provider
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_REQUEST_MANAGER_H_