Only distill unread items

ios/chrome/browser/reading_list/url_downloader.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 "ios/chrome/browser/reading_list/url_downloader.h"
 
 #include <string>
 #include <vector>
 
 #include "base/files/file_path.h"
@@ skipping 32 matching lines @@
   task_tracker_.PostTaskAndReplyWithResult(
       web::WebThread::GetTaskRunnerForThread(web::WebThread::FILE).get(),
       FROM_HERE,
       base::Bind(&base::PathExists,
                  reading_list::OfflinePageAbsolutePath(base_directory_, url)),
       callback);
 }
 
 void URLDownloader::RemoveOfflineURL(const GURL& url) {
   // Remove all download tasks for this url as it would be pointless work.
-  tasks_.erase(
-      std::remove(tasks_.begin(), tasks_.end(), std::make_pair(DOWNLOAD, url)),
-      tasks_.end());
+  CancelDownloadOfflineURL(url);
   tasks_.push_back(std::make_pair(DELETE, url));
   HandleNextTask();
 }
 
 void URLDownloader::DownloadOfflineURL(const GURL& url) {
   if (std::find(tasks_.begin(), tasks_.end(), std::make_pair(DOWNLOAD, url)) ==
       tasks_.end()) {
     tasks_.push_back(std::make_pair(DOWNLOAD, url));
     HandleNextTask();
   }
 }
 
+void URLDownloader::CancelDownloadOfflineURL(const GURL& url) {
+  tasks_.erase(
+      std::remove(tasks_.begin(), tasks_.end(), std::make_pair(DOWNLOAD, url)),
+      tasks_.end());
+}
+
 void URLDownloader::DownloadCompletionHandler(const GURL& url,
                                               const std::string& title,
                                               SuccessState success) {
   DCHECK(working_);
 
   auto post_delete = base::Bind(
       [](URLDownloader* _this, const GURL& url, const std::string& title,
          SuccessState success) {
         _this->download_completion_.Run(
             url, success, reading_list::OfflinePagePath(url), title);
@@ skipping 150 matching lines @@
 }
 
 bool URLDownloader::SaveHTMLForURL(std::string html, const GURL& url) {
   if (html.empty()) {
     return false;
   }
   base::FilePath path =
       reading_list::OfflinePageAbsolutePath(base_directory_, url);
   return base::WriteFile(path, html.c_str(), html.length()) > 0;
 }