drive: Event logger for chrome:drive-internals.

chrome/browser/chromeos/drive/event_logger.cc

+// Copyright (c) 2012 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.
+
+#include "chrome/browser/chromeos/drive/event_logger.h"
+
+namespace drive {
+
+EventLogger::Event::Event(int id, const std::string& what)
+    : id(id),
+      when(base::Time::Now()),
+      what(what) {
+}
+
+EventLogger::EventLogger(size_t history_size)
+    : history_size_(history_size),
+      next_event_id_(0) {
+}
+
+EventLogger::~EventLogger() {
+}
+
+void EventLogger::Log(const std::string& what) {
+  history_.push_back(Event(next_event_id_, what));
+  ++next_event_id_;
+  if (history_.size() > history_size_)
+    history_.pop_front();
+}
+
+}  // namespace drive