[Offline Pages] Create a event/activity logger

components/offline_pages/offline_event_logger.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 COMPONENTS_OFFLINE_PAGES_OFFLINE_EVENT_LOGGER_H_
+#define COMPONENTS_OFFLINE_PAGES_OFFLINE_EVENT_LOGGER_H_
+
+#include <deque>
+#include <string>
+#include <vector>
+
+#include "base/macros.h"
+
+namespace offline_pages {
+
+class OfflineEventLogger {

[Pete Williamson, 2016/06/24 00:38:32]

A class header comment with usage notes would be nice here.

For instance, maybe SetLogging() and GetLogs() is called by
chrome://chrome-offlining.
Maybe how to put logs into the logger from the code being logged, and some
guidance about what to log. (Do we manually call to log interesting events?  Are
all function calls automatically traced into the log?)
Maybe some hint of how much we can log before the log cycles over.

[chili, 2016/06/24 02:45:51]

Done.

+ public:
+  OfflineEventLogger();
+
+  ~OfflineEventLogger();
+
+  // Clears the recorded activities.
+  void Clear();
+
+  // Turns logging on/off.
+  void SetIsLogging(bool is_logging);
+
+  // Dumps the current activity list into |records|.
+  void GetLogs(std::vector<std::string>& records);
+
+ protected:
+  // Write the activity into the cycling log if we are currently logging.
+  void RecordActivity(const std::string& activity);
+
+ private:
+  // Recorded offline page activities.
+  std::deque<std::string> activities_;

[Pete Williamson, 2016/06/24 00:38:32]

I like your choice of a deque here, it fits perfectly!

[chili, 2016/06/24 02:45:51]

Acknowledged. ^_^

+
+  // Whether we are currently recording logs or not.
+  bool is_logging_;
+};
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_EVENT_LOGGER_H_