Retrieving Chrome Variations seed from server and storing in local prefs. Loading seed data from lo…

chrome/browser/metrics/variations_service.h

+// 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.
+
+#ifndef CHROME_BROWSER_METRICS_VARIATIONS_SERVICE_H_
+#define CHROME_BROWSER_METRICS_VARIATIONS_SERVICE_H_
+#pragma once
+
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/metrics/proto/trials_seed.pb.h"
+#include "content/public/common/url_fetcher_delegate.h"
+
+class PrefService;
+
+class VariationsService : public content::URLFetcherDelegate {
+ public:
+  VariationsService();
+  virtual ~VariationsService();
+
+  // Loads the Variations seed data from the given local prefs. If there is a
+  // problem with loading, the pref value is cleared.
+  void LoadVariationsSeed(PrefService* local_prefs);
+
+  // Starts the fetching process, where |OnURLFetchComplete| is called with the
+  // response.
+  void StartFetchingVariationsSeed();
+
+  // content::URLFetcherDelegate implementation:
+  virtual void OnURLFetchComplete(const content::URLFetcher* source) OVERRIDE;
+
+

[MAD, 2012/05/04 12:29:57]

Single empty line please...

[jwd, 2012/05/04 19:33:06]

Done.

+  // Register Variations related prefs in Local State.
+  static void RegisterPrefs(PrefService* prefs);
+
+ private:
+  // Store the given seed data to the given local prefs. Note that |seed_data|
+  // is assumed to be the raw serialized protobuf data stored in a string. It
+  // will Base64Encoded for storage. If the string is invalid or the encoding

[MAD, 2012/05/04 12:29:57]

will BE Base...

[jwd, 2012/05/04 19:33:06]

Done.

+  // fails, the |local_prefs| is left as is.
+  void StoreSeedData(const std::string& seed_data, PrefService* local_prefs);
+
+  // Contains the current seed request. Will only have a value while a request
+  // is pending, and will be reset by |OnURLFetchComplete|.
+  scoped_ptr<content::URLFetcher> pending_seed_request_;
+
+  // The variations seed data being used for this session.
+  chrome_variations::TrialsSeed variations_seed_;

[MAD, 2012/05/04 12:29:57]

I don't think we will use the variations_seed_ data within the session. I think
it's fine to keep it for now since we don't do anything with the data we fetch
yet, but I'm guessing we'll remove it once we add the code to use it because I
think we will use it as soon as we get it so we won't need to keep it...

[jwd, 2012/05/04 19:33:06]

Based on in person conversation, this won't be needed. I'm keeping it here for
now, but adding a TODO to remove it.

+};
+
+#endif  // CHROME_BROWSER_METRICS_VARIATIONS_SERVICE_H_