Moves manifest parsing to a new class, Reader.

mojo/services/catalog/reader.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 MOJO_SERVICES_CATALOG_READER_H_
+#define MOJO_SERVICES_CATALOG_READER_H_
+
+#include "base/callback.h"
+#include "base/files/file_path.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/values.h"
+
+namespace base {
+class TaskRunner;
+}
+
+namespace catalog {
+
+class Entry;
+
+// Encapsulates manifest reading.
+class Reader {
+ public:
+  using ReadManifestCallback =
+      base::Callback<void(scoped_ptr<Entry> entry)>;
+
+  // Loads manifests relative to |package_path|. Performs file operations on
+  // |file_task_runner|.
+  Reader(const base::FilePath& package_path,
+         base::TaskRunner* file_task_runner);
+  ~Reader();
+
+  // Attempts to load a manifest for |name|, and returns an Entry built from the
+  // metadata it contains via |callback|.
+  void Read(const std::string& name,
+            const ReadManifestCallback& callback);
+
+ private:
+  // Construct a manifest path for the application named |name| within
+  // |package_path_|.
+  base::FilePath GetManifestPath(const std::string& name) const;
+
+  base::FilePath package_path_;
+  base::TaskRunner* file_task_runner_;
+  base::WeakPtrFactory<Reader> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(Reader);
+};
+
+}  // namespace catalog
+
+#endif  // MOJO_SERVICES_CATALOG_READER_H_