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

chrome/browser/metrics/variations_service.cc

Index: chrome/browser/metrics/variations_service.cc
diff --git a/chrome/browser/metrics/variations_service.cc b/chrome/browser/metrics/variations_service.cc
index 5ee2ee13fa8ec28026d9dd672fb2121520cf63ea..0682f3b74726c8794f4e9e7b5e6ff20d1abb20d5 100644
--- a/chrome/browser/metrics/variations_service.cc
+++ b/chrome/browser/metrics/variations_service.cc
@@ -16,10 +16,12 @@
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/metrics/proto/trials_seed.pb.h"
 #include "chrome/browser/prefs/pref_service.h"
+#include "chrome/common/chrome_notification_types.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/metrics/experiments_helper.h"
 #include "chrome/common/pref_names.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/browser/notification_service.h"
 #include "content/public/common/url_fetcher.h"
 #include "googleurl/src/gurl.h"
 #include "net/base/load_flags.h"
@@ -99,6 +101,8 @@ GURL GetVariationsServerURL() {
 
 VariationsService::VariationsService()
     : variations_server_url_(GetVariationsServerURL()) {
+  registrar_.Add(this, chrome::NOTIFICATION_UPGRADE_RECOMMENDED,
+                 content::NotificationService::AllSources());
 }
 
 VariationsService::~VariationsService() {}
@@ -140,6 +144,27 @@ void VariationsService::StartRepeatedVariationsSeedFetch() {
                this, &VariationsService::FetchVariationsSeed);
 }
 
+// static
+void VariationsService::RegisterPrefs(PrefService* prefs) {
+  prefs->RegisterStringPref(prefs::kVariationsSeed, std::string());
+  prefs->RegisterInt64Pref(prefs::kVariationsSeedDate,
+                           base::Time().ToInternalValue());
+}
+
+void VariationsService::Observe(int type,
+                                const content::NotificationSource& source,
+                                const content::NotificationDetails& details) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  DCHECK(type == chrome::NOTIFICATION_UPGRADE_RECOMMENDED);
+  // An upgrade is ready, so attempt to fetch the Variations seed in case there
+  // were updates.
+  FetchVariationsSeed();
+
+  // Since we explicitly call FetchVariationsSeed here, we can reset the timer
+  // so that we don't retry for another full period.
+  timer_.Reset();
+}
+
 void VariationsService::FetchVariationsSeed() {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
 
@@ -186,13 +211,6 @@ void VariationsService::OnURLFetchComplete(const net::URLFetcher* source) {
   StoreSeedData(seed_data, response_date, g_browser_process->local_state());
 }
 
-// static
-void VariationsService::RegisterPrefs(PrefService* prefs) {
-  prefs->RegisterStringPref(prefs::kVariationsSeed, std::string());
-  prefs->RegisterInt64Pref(prefs::kVariationsSeedDate,
-                           base::Time().ToInternalValue());
-}
-
 bool VariationsService::StoreSeedData(const std::string& seed_data,
                                       const base::Time& seed_date,
                                       PrefService* local_prefs) {