Upstream oodles of Chrome for Android code into Chromium.

chrome/browser/android/history_report/delta_file_backend_leveldb.h

+// Copyright 2015 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_ANDROID_HISTORY_REPORT_DELTA_FILE_BACKEND_LEVELDB_H_
+#define CHROME_BROWSER_ANDROID_HISTORY_REPORT_DELTA_FILE_BACKEND_LEVELDB_H_
+
+#include <vector>
+
+#include "base/files/file_path.h"
+#include "base/memory/scoped_ptr.h"
+
+class GURL;
+
+namespace leveldb {
+class DB;
+}
+
+namespace history_report {
+
+class DeltaFileEntryWithData;
+
+// Backend for delta file.
+class DeltaFileBackend {
+ public:
+  explicit DeltaFileBackend(const base::FilePath& dir);
+  ~DeltaFileBackend();
+
+  // Adds new addition entry to delta file
+  void PageAdded(const GURL& url);
+  // Adds new deletion entry to delta file
+  void PageDeleted(const GURL& url);
+  // Removes all delta file entries with
+  // sequence number <= min(|lower_bound|, max sequence number - 1).
+  // Returns max sequence number in delta file.
+  int64 Trim(int64 lower_bound);
+  // Recreates delta file using given |urls|.
+  bool Recreate(const std::vector<std::string>& urls);
+  // Provides up to |limit| delta file entries with
+  // sequence number > |last_seq_no|.
+  scoped_ptr<std::vector<DeltaFileEntryWithData> > Query(int64 last_seq_no,
+                                                         int32 limit);
+  // Removes all entries from delta file
+  void Clear();
+
+  // Dumps internal state to string. For debuging.
+  std::string Dump();
+
+ private:
+  // Starts delta file backend.
+  bool Init();
+
+  bool EnsureInitialized();
+
+  class DigitsComparator;
+
+  base::FilePath path_;
+  scoped_ptr<leveldb::DB> db_;
+  scoped_ptr<DigitsComparator> leveldb_cmp_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeltaFileBackend);
+};
+
+}  // namespace history_report
+
+#endif  // CHROME_BROWSER_ANDROID_HISTORY_REPORT_DELTA_FILE_BACKEND_LEVELDB_H_