Defer ARC file system operations while ARC is booting.

chrome/browser/chromeos/arc/fileapi/arc_deferred_file_system_operation_runner.h

+// Copyright 2017 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_ARC_FILEAPI_ARC_DEFERRED_FILE_SYSTEM_OPERATION_RUNNER_H_
+#define CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_DEFERRED_FILE_SYSTEM_OPERATION_RUNNER_H_
+
+#include <string>
+#include <vector>
+
+#include "base/callback_forward.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "chrome/browser/chromeos/arc/arc_session_manager.h"
+#include "components/arc/arc_service.h"
+#include "components/arc/common/file_system.mojom.h"
+#include "components/arc/file_system/arc_file_system_operation_runner.h"
+#include "components/arc/instance_holder.h"
+
+namespace arc {
+
+// Implements deferred ARC file system operations.
+//
+// When ARC is disabled or ARC has already booted, file system operations are
+// performed immediately. While ARC boot is under progress, file operations are
+// deferred until ARC boot finishes or the user disables ARC.
+//
+// This file system operation runner provides better UX when the user attempts
+// to perform file operations while ARC is booting. For example:
+//
+// - Media views are mounted in Files app soon after the user logs into
+//   the system. If the user attempts to open media views before ARC boots,
+//   a spinner is shown until file system gets ready because ReadDirectory
+//   operations are deferred.
+// - When an Android content URL is opened soon after the user logs into
+//   the system (because the user opened the tab before they logged out for
+//   instance), the tab keeps loading until ARC boot finishes, instead of
+//   failing immediately.
+//
+// All member functions must be called on the UI thread.
+class ArcDeferredFileSystemOperationRunner
+    : public ArcFileSystemOperationRunner,
+      public ArcSessionManager::Observer,
+      public InstanceHolder<mojom::FileSystemInstance>::Observer {
+ public:
+  explicit ArcDeferredFileSystemOperationRunner(
+      ArcBridgeService* bridge_service);
+  ~ArcDeferredFileSystemOperationRunner() override;
+
+  // ArcFileSystemOperationRunner overrides:
+  void GetFileSize(const GURL& url,
+                   const GetFileSizeCallback& callback) override;
+  void OpenFileToRead(const GURL& url,
+                      const OpenFileToReadCallback& callback) override;
+  void GetDocument(const std::string& authority,
+                   const std::string& document_id,
+                   const GetDocumentCallback& callback) override;
+  void GetChildDocuments(const std::string& authority,
+                         const std::string& parent_document_id,
+                         const GetChildDocumentsCallback& callback) override;
+
+  // ArcSessionManager::Observer overrides:
+  void OnArcOptInChanged(bool enabled) override;
+
+  // InstanceHolder<mojom::FileSystemInstance>::Observer overrides:
+  void OnInstanceReady() override;
+  void OnInstanceClosed() override;
+
+ private:
+  friend class ArcDeferredFileSystemOperationRunnerTest;
+
+  // Constructor called from unit tests.
+  ArcDeferredFileSystemOperationRunner(ArcBridgeService* bridge_service,
+                                       bool observe_events);
+
+  // Called whenever ARC states related to |should_defer_| are changed.
+  void OnStateChanged();
+
+  // Enables/disables deferring.
+  void SetShouldDefer(bool should_defer);
+
+  // Indicates if this instance should register observers to receive events.
+  // Usually true, but set to false in unit tests.
+  bool observe_events_;
+
+  // Set to true if operations should be deferred at this moment.
+  bool should_defer_ = true;
+
+  // List of deferred operations.
+  std::vector<base::Closure> deferred_operations_;
+
+  base::WeakPtrFactory<ArcDeferredFileSystemOperationRunner> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ArcDeferredFileSystemOperationRunner);
+};
+
+}  // namespace arc
+
+#endif  // CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_DEFERRED_FILE_SYSTEM_OPERATION_RUNNER_H_