mediaview: Introduce ArcDocumentsProviderRoot.

chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root_map.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_MAP_H_
+#define CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_DOCUMENTS_PROVIDER_ROOT_MAP_H_
+
+#include <map>
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "base/files/file_path.h"
+#include "base/macros.h"
+
+namespace storage {
+class FileSystemURL;
+}  // namespace storage
+
+namespace arc {
+
+class ArcDocumentsProviderRoot;
+
+// Container of ArcDocumentsProviderRoot instances.
+//
+// This class is thread-safe, but ArcDocumentsProviderRoot must be accessed
+// only on the IO thread anyway.
+class ArcDocumentsProviderRootMap {
+ public:
+  ArcDocumentsProviderRootMap();
+  ~ArcDocumentsProviderRootMap();
+
+  // Looks up a root corresponding to |authority| and |root_document_id|.
+  // Returns nullptr if no such root is registered.
+  ArcDocumentsProviderRoot* Lookup(const std::string& authority,

[Luis Héctor Chávez, 2016/12/15 21:26:10]

I couldn't find any calls for this function from anywhere outside this class in
either this or the next CL. I don't exactly have strong opinions on this, but
how about you move it to the anonymous namespace and pass in |map_| as
const-reference? (or just move this implementation into ParseAndLookup). 

[Shuhei Takahashi, 2016/12/16 03:21:12]

Makes sense. I've just moved the implementation into ParseAndLoopup. Thanks!

+                                   const std::string& root_document_id) const;
+
+  // Looks up a root corresponding to |url|.
+  // |path| is set to the remaining path part of |url|.
+  // Returns nullptr if |url| is invalid or no corresponding root is registered.
+  ArcDocumentsProviderRoot* ParseAndLookup(const storage::FileSystemURL& url,
+                                           base::FilePath* path) const;
+
+ private:
+  // Key is (authority, root_document_id).
+  using Key = std::pair<std::string, std::string>;
+  std::map<Key, std::unique_ptr<ArcDocumentsProviderRoot>> map_;
+
+  DISALLOW_COPY_AND_ASSIGN(ArcDocumentsProviderRootMap);
+};
+
+}  // namespace arc
+
+#endif  // CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_DOCUMENTS_PROVIDER_ROOT_MAP_H_