Media Galleries: Initial media scanner implementation.

chrome/browser/media_galleries/media_folder_finder.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_MEDIA_GALLERIES_MEDIA_FOLDER_FINDER_H_
+#define CHROME_BROWSER_MEDIA_GALLERIES_MEDIA_FOLDER_FINDER_H_
+
+#include <map>
+#include <stack>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/files/file_path.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "chrome/browser/media_galleries/media_scan_types.h"
+
+// MediaFolderFinder scans local hard drives and look for folders that contain
+// media files.
+class MediaFolderFinder {
+ public:
+  typedef std::map<base::FilePath, MediaGalleryScanResult>
+      MediaFolderFinderResults;
+  typedef base::Callback<void(bool /*success*/,
+                              const MediaFolderFinderResults& /*results*/)>
+      MediaFolderFinderResultsCallback;
+  typedef base::Callback<MediaGalleryScanFileType(const base::FilePath&)>
+      FilterCallback;
+
+  // Set up a scan with a given set of |roots| as starting points.
+  // The elements of |roots| should not overlap and should be absolute.
+  // |callback| will get called when the scan finishes. If the object is deleted
+  // before it finishes, the scan will stop and |callback| will get called with
+  // success = false.
+  MediaFolderFinder(const std::vector<base::FilePath>& roots,
+                    const MediaFolderFinderResultsCallback& callback);
+  ~MediaFolderFinder();
+
+  // Start the scan.
+  void StartScan();
+
+ private:
+  enum ScanState {
+    SCAN_STATE_NOT_STARTED,
+    SCAN_STATE_STARTED,
+    SCAN_STATE_FINISHED,
+  };
+
+  // Scan a folder from |folders_to_scan_|.
+  void ScanFolder();
+
+  // Callback that returns the |scan_result| for |path| and the |new_folders|
+  // to scan in future calls to ScanFolder().
+  void GotScanResults(const base::FilePath& path,
+                      const MediaGalleryScanResult* scan_result,
+                      const std::vector<base::FilePath>* new_folders);
+
+  const MediaFolderFinderResultsCallback results_callback_;
+  MediaFolderFinderResults results_;
+
+  std::stack<base::FilePath> folders_to_scan_;
+  ScanState scan_state_;
+
+  // Token to make sure all calls with |filter_callback_| are on the same
+  // sequence.
+  base::SequencedWorkerPool::SequenceToken token_;
+
+  // Callback used to filter through files and make sure they are media files.
+  FilterCallback filter_callback_;
+
+  base::WeakPtrFactory<MediaFolderFinder> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaFolderFinder);
+};
+
+#endif  // CHROME_BROWSER_MEDIA_GALLERIES_MEDIA_FOLDER_FINDER_H_