ChromeOS: Implement periodic timezone refresh on geolocation data.

chromeos/timezone/timezone_resolver.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 CHROMEOS_TIMEZONE_TIMEZONE_RESOLVER_H_
+#define CHROMEOS_TIMEZONE_TIMEZONE_RESOLVER_H_
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/threading/thread_checker.h"
+#include "chromeos/chromeos_export.h"
+#include "url/gurl.h"
+
+class PrefRegistrySimple;
+class PrefService;
+
+namespace net {
+class URLRequestContextGetter;
+}
+
+namespace chromeos {
+
+struct TimeZoneResponseData;
+
+// This class implements periodic timezone synchronization.
+class CHROMEOS_EXPORT TimeZoneResolver {
+ public:
+  class TimeZoneResolverImpl;
+
+  // This callback will be called when new timezone arrives.
+  typedef base::Callback<void(const TimeZoneResponseData*)>
+      ApplyTimeZoneCallback;
+
+  // chromeos::DelayNetworkCall cannot be used directly due to link
+  // restrictions.
+  typedef base::Callback<void(const base::Closure&)> DelayNetworkCallClosure;
+
+  // This is a LocalState preference to store base::Time value of the last
+  // request.
+  // It is used to limit request rate on browser restart.
+  static const char kLastTimeZoneRefreshTime[];
+
+  TimeZoneResolver(net::URLRequestContextGetter* context,
+                   const GURL& url,
+                   const ApplyTimeZoneCallback& apply_timezone,
+                   const DelayNetworkCallClosure& delay_network_call,
+                   PrefService* local_state);
+  ~TimeZoneResolver();
+
+  // Starts periodic timezone refresh.
+  void Start();
+
+  // Cancels current request and stops periodic timezone refresh.
+  void Stop();
+
+  // Register prefs to LocalState.
+  static void RegisterPrefs(PrefRegistrySimple* registry);
+
+  // Expose internal fuctions for testing.
+  static int MaxRequestsCountForIntervalForTesting(
+      const double interval_seconds);
+  static int IntervalForNextRequestForTesting(const int requests);
+
+ private:
+  net::URLRequestContextGetter* const context_;

[Dmitry Polukhin, 2015/01/28 12:10:10]

It looks like it should be scoped_refptr<net::URLRequestContextGetter>, here and
in other places where you store it (i.e. not only pass it).

[Alexander Alekseev, 2015/01/28 17:57:55]

Done.

+  const GURL url_;
+
+  const ApplyTimeZoneCallback apply_timezone_;
+  const DelayNetworkCallClosure delay_network_call_;
+  PrefService* local_state_;

[Dmitry Polukhin, 2015/01/28 12:10:10]

Suggestion, I don't like having all these data members in 2 classes (interface +
impl). Can we always create impl and pass all params but initialize impl it only
if needed?

[Alexander Alekseev, 2015/01/28 17:57:55]

The idea was to use RAII, so that implementation would exist only of periodic
resolve is started.

I've removed data copying, and now implementation would get all the data from
TimeZoneResolver object.

+
+  scoped_ptr<TimeZoneResolverImpl> implementation_;
+
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(TimeZoneResolver);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_TIMEZONE_TIMEZONE_RESOLVER_H_