Have the VariationsService attempt to fetch the seed when an update is ready.

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_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/field_trial.h"
 #include "base/time.h"
 #include "base/timer.h"
 #include "chrome/browser/metrics/proto/study.pb.h"
 #include "chrome/browser/metrics/proto/trials_seed.pb.h"
 #include "chrome/common/chrome_version_info.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
 #include "googleurl/src/gurl.h"
 #include "net/url_request/url_fetcher_delegate.h"
 
 class PrefService;
 
 namespace net {
 class URLFetcher;
 }  // namespace net
 
 namespace chrome_variations {
 
 // Used to setup field trials based on stored variations seed data, and fetch
 // new seed data from the variations server.
-class VariationsService : public net::URLFetcherDelegate {
+class VariationsService : public net::URLFetcherDelegate,
+                          public content::NotificationObserver {
  public:
   VariationsService();
   virtual ~VariationsService();
 
   // Creates field trials based on Variations Seed loaded from local prefs. If
   // there is a problem loading the seed data, all trials specified by the seed
   // may not be created.
   bool CreateTrialsFromSeed(PrefService* local_prefs);
 
   // Calls FetchVariationsSeed once and repeats this periodically. See
   // implementation for details on the period.
   void StartRepeatedVariationsSeedFetch();
 
   // Starts the fetching process once, where |OnURLFetchComplete| is called with
   // the response.
   void FetchVariationsSeed();

[Alexei Svitkine (slow), 2012/07/23 15:32:13]

I think this should be private too. Sorry that I didn't catch this earlier.

[SteveT, 2012/07/23 15:44:14]

Done.

 
   // net::URLFetcherDelegate implementation:
   virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;

[Alexei Svitkine (slow), 2012/07/23 15:32:13]

This should be private too, I think.

[SteveT, 2012/07/23 15:44:14]

Done.

 
   // Register Variations related prefs in Local State.
   static void RegisterPrefs(PrefService* prefs);
 
+  // Overridden from content::NotificationObserver:
+  virtual void Observe(int type,

[Alexei Svitkine (slow), 2012/07/23 14:42:43]

Does this need to be public?

[SteveT, 2012/07/23 15:24:31]

I guess we can make this private and friend it if we test with it.

[Alexei Svitkine (slow), 2012/07/23 15:32:13]

I think that makes sense to do. The existing tests are already friends.

We don't need to expose this to the outside world.

[SteveT, 2012/07/23 15:44:14]

SGTM. Will add the FRIEND stuff when I add the test.

+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
  private:
   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyChannel);
   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyLocale);
   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyPlatform);
   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyVersion);
   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyVersionWildcards);
   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, CheckStudyStartDate);
   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, IsStudyExpired);
   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, LoadSeed);
   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, StoreSeed);
@@ skipping 58 matching lines @@
   // is pending, and will be reset by |OnURLFetchComplete|.
   scoped_ptr<net::URLFetcher> pending_seed_request_;
 
   // The URL to use for querying the variations server.
   GURL variations_server_url_;
 
   // The timer used to repeatedly ping the server. Keep this as an instance
   // member so if VariationsService goes out of scope, the timer is
   // automatically cancelled.
   base::RepeatingTimer<VariationsService> timer_;
+
+  content::NotificationRegistrar registrar_;

[Alexei Svitkine (slow), 2012/07/23 14:42:43]

Nit: Add a comment.

[SteveT, 2012/07/23 15:24:31]

Done.

 };
 
 }  // namespace chrome_variations
 
 #endif  // CHROME_BROWSER_METRICS_VARIATIONS_SERVICE_H_