Don't ping for extension blacklist when no extensions are installed....

chrome/browser/extensions/extension_updater.cc

 // Copyright (c) 2009 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.
 
 #include "chrome/browser/extensions/extension_updater.h"
 
 #include <algorithm>
 #include <set>
 
 #include "base/logging.h"
@@ skipping 503 matching lines @@
   // Save the last check time, and schedule the next check.
   int64 now = Time::Now().ToInternalValue();
   prefs_->SetInt64(kLastExtensionsUpdateCheck, now);
   ScheduleNextCheck(TimeDelta::FromSeconds(frequency_seconds_));
 }
 
 void ExtensionUpdater::CheckNow() {
   // Generate a set of update urls for loaded extensions.
   std::set<GURL> urls;
 
-  if (blacklist_checks_enabled_) {
+  if (blacklist_checks_enabled_ && service_->HasInstalledExtensions()) {
     urls.insert(GetBlacklistUpdateUrl(
         prefs_->GetString(kExtensionBlacklistUpdateVersion)));
   }
 
   int no_url_count = 0;
   int google_url_count = 0;
   int other_url_count = 0;
   int theme_count = 0;
 
   const ExtensionList* extensions = service_->extensions();
@@ skipping 177 matching lines @@
     extension_fetcher_.reset(
         URLFetcher::Create(kExtensionFetcherId, url, URLFetcher::GET, this));
     extension_fetcher_->set_request_context(
         Profile::GetDefaultRequestContext());
     extension_fetcher_->set_load_flags(net::LOAD_DO_NOT_SEND_COOKIES |
                                        net::LOAD_DO_NOT_SAVE_COOKIES);
     extension_fetcher_->Start();
     current_extension_fetch_ = ExtensionFetch(id, url, hash, version);
   }
 }