[NTP::Downloads] Do not fetch Offline Pages when their model is loaded.

chrome/browser/ntp_snippets/download_suggestions_provider.cc

 // Copyright 2016 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/ntp_snippets/download_suggestions_provider.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 301 matching lines @@
       }
     }
   }
 
   callback.Run(std::move(suggestions));
 }
 
 void DownloadSuggestionsProvider::OfflinePageModelLoaded(
     offline_pages::OfflinePageModel* model) {
   DCHECK_EQ(offline_page_model_, model);
-  AsynchronouslyFetchOfflinePagesDownloads(/*notify=*/true);
+  // Ignored. We issue a fetch in the constructor (or when Downloads Manager is
+  // loaded) and Offline Page model answers asynchronously once it has been
+  // loaded.
 }
 
 void DownloadSuggestionsProvider::OfflinePageAdded(
     offline_pages::OfflinePageModel* model,
     const offline_pages::OfflinePageItem& added_page) {
   DCHECK_EQ(offline_page_model_, model);
   if (!IsClientIdForOfflinePageDownload(model->GetPolicyController(),
                                         added_page.client_id)) {
     return;
   }
@@ skipping 476 matching lines @@
 void DownloadSuggestionsProvider::UnregisterDownloadItemObservers() {
   DCHECK_NE(download_manager_, nullptr);
 
   std::vector<DownloadItem*> all_downloads;
   download_manager_->GetAllDownloads(&all_downloads);
 
   for (DownloadItem* item : all_downloads) {
     item->RemoveObserver(this);
   }
 }