Adds a Fetch() method to the ContentSuggestionService which asks any provider to provide more conte…

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"
 #include "base/feature_list.h"
 #include "base/guid.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
@@ skipping 137 matching lines @@
     const ContentSuggestion::ID& suggestion_id,
     const ImageFetchedCallback& callback) {
   // TODO(vitaliii): Fetch proper thumbnail from OfflinePageModel once it is
   // available there.
   // TODO(vitaliii): Provide site's favicon for assets downloads. See
   // crbug.com/631447.
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(callback, gfx::Image()));
 }
 
+void DownloadSuggestionsProvider::Fetch(
+    const ntp_snippets::Category& category,
+    const std::set<std::string>& known_suggestion_ids,
+    FetchingCallback callback) {
+  NOTREACHED();
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE,
+      base::Bind(callback, base::Passed(std::vector<ContentSuggestion>())));
+}
+
 void DownloadSuggestionsProvider::ClearHistory(
     base::Time begin,
     base::Time end,
     const base::Callback<bool(const GURL& url)>& filter) {
   cached_offline_page_downloads_.clear();
   cached_asset_downloads_.clear();
   // This will trigger an asynchronous re-fetch.
   ClearDismissedSuggestionsForDebugging(provided_category_);
 }
 
@@ skipping 445 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);
 }