Adding in memory log of history visit database. This...

chrome/browser/history/visit_log.h

+// Copyright (c) 2009 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_HISTORY_VISIT_LOG_H_
+#define CHROME_BROWSER_HISTORY_VISIT_LOG_H_
+
+#include "base/basictypes.h"
+
+namespace history {
+
+// VisitLog provides support for basic in-memory logging of history visit
+// events. It keeps a circular buffer where the recent visit events is
+// recorded.
+
+// This class is not thread safe.
+class VisitLog {
+ public:
+  VisitLog();
+  ~VisitLog();
+
+  enum EventType {
+    NO_OP,
+    ADD_VISIT,
+    DELETE_VISIT,
+    UPDATE_VISIT,
+    SELECT_VISIT,
+  };
+
+  static int events_buffer_size() { return kVisitLogBufferSize; }
+  unsigned char* events() { return events_; }
+  int index() { return index_; }
+
+  int num_add() { return num_add_; }
+  int num_delete() { return num_delete_; }
+  int num_update() { return num_update_; }
+  int num_select() { return num_select_; }
+
+  void AddEvent(EventType event);
+
+ private:
+  // Circular buffer of recent events.
+  static const int kVisitLogBufferSize = 4096;
+  unsigned char events_[kVisitLogBufferSize];
+  int index_;
+
+  // Event counters
+  int num_add_;
+  int num_delete_;
+  int num_update_;
+  int num_select_;
+
+  DISALLOW_COPY_AND_ASSIGN(VisitLog);
+};
+
+void InitVisitLog(VisitLog* vlog);
+void AddEventToVisitLog(VisitLog::EventType event);
+
+}  // namespace history
+
+#endif  // CHROME_BROWSER_HISTORY_VISIT_LOG_H_