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

chrome/browser/metrics/variations_service.h

Index: chrome/browser/metrics/variations_service.h
diff --git a/chrome/browser/metrics/variations_service.h b/chrome/browser/metrics/variations_service.h
index a431a6dd1498625bf167cd921b22b90428d064bb..014ba46a011d421977b3e40b6dd377bd7e55568a 100644
--- a/chrome/browser/metrics/variations_service.h
+++ b/chrome/browser/metrics/variations_service.h
@@ -16,6 +16,8 @@
 #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"
 
@@ -29,7 +31,8 @@ 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();
@@ -53,6 +56,11 @@ class VariationsService : public net::URLFetcherDelegate {
   // 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);
@@ -131,6 +139,8 @@ class VariationsService : public net::URLFetcherDelegate {
   // 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