mediaview: Implement ArcDocumentsProviderRoot.

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

 // Copyright 2016 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_DOCUMENTS_PROVIDER_ROOT_H_
 #define CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_DOCUMENTS_PROVIDER_ROOT_H_
 
+#include <memory>
 #include <string>
+#include <vector>
 
 #include "base/files/file_path.h"
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/optional.h"
+#include "components/arc/common/file_system.mojom.h"
 #include "storage/browser/fileapi/async_file_util.h"
 
 namespace arc {
 
+class ArcDocumentsProviderDocument;
+
 // Represents a file system root in Android Documents Provider.
 //
 // All methods must be called on the IO thread.
+// If this object is deleted while there are in-flight operations, callbacks
+// for those operations will be never called.
 class ArcDocumentsProviderRoot {
  public:
   using GetFileInfoCallback = storage::AsyncFileUtil::GetFileInfoCallback;
   using ReadDirectoryCallback = storage::AsyncFileUtil::ReadDirectoryCallback;
 
   ArcDocumentsProviderRoot(const std::string& authority,
                            const std::string& root_document_id);
   ~ArcDocumentsProviderRoot();
 
   // Queries information of a file just like AsyncFileUtil.GetFileInfo().
   void GetFileInfo(const base::FilePath& path,
                    const GetFileInfoCallback& callback);
 
   // Queries a list of files under a directory just like
   // AsyncFileUtil.ReadDirectory().
   void ReadDirectory(const base::FilePath& path,
                      const ReadDirectoryCallback& callback);
 
  private:
+  void GetFileInfoAfterCacheUpdate(const base::FilePath& path,
+                                   const GetFileInfoCallback& callback);
+  void GetFileInfoWithDocument(const GetFileInfoCallback& callback,
+                               mojom::DocumentPtr document);
+
+  void ReadDirectoryAfterCacheUpdate(const base::FilePath& path,
+                                     const ReadDirectoryCallback& callback);
+  void ReadDirectoryWithChildDocuments(
+      const base::FilePath& path,
+      const ReadDirectoryCallback& callback,
+      base::Optional<std::vector<mojom::DocumentPtr>> children);
+
+  void UpdateDirectoryCacheUpTo(const base::FilePath& path,

[hashimoto, 2016/12/19 06:40:48]

Please add a comment to describe what this method does.
What does "cache" mean?
What does "up to" mean?

[Shuhei Takahashi, 2016/12/19 10:01:56]

N/A

+                                const base::Closure& callback);
+  void UpdateDirectoryCacheIter(const base::FilePath& parent_directory_path,

[hashimoto, 2016/12/19 06:40:48]

What does "iter" mean?
Generally speaking, you should avoid abbreviation
https://google.github.io/styleguide/cppguide.html#General_Naming_Rules

[Shuhei Takahashi, 2016/12/19 10:01:56]

N/A

+                                const base::FilePath& remaining_path,
+                                const base::Closure& callback);
+  void UpdateDirectoryCacheIterWithChildDocuments(
+      const base::FilePath& parent_directory_path,
+      const base::FilePath& remaining_path,
+      const base::Closure& callback,
+      base::Optional<std::vector<mojom::DocumentPtr>> children);
+
+  const std::string authority_;
+  const std::unique_ptr<ArcDocumentsProviderDocument> root_directory_;
+  base::WeakPtrFactory<ArcDocumentsProviderRoot> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(ArcDocumentsProviderRoot);
 };
 
 }  // namespace arc
 
 #endif  // CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_DOCUMENTS_PROVIDER_ROOT_H_