Popular sites on the NTP: re-download popular suggestions once per Chrome run

chrome/browser/android/popular_sites.cc

 // Copyright 2013 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/android/popular_sites.h"
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/json/json_reader.h"
@@ skipping 124 matching lines @@
       thumbnail_url(thumbnail_url) {}
 
 PopularSites::Site::~Site() {}
 
 PopularSites::PopularSites(Profile* profile,
                            const std::string& filename,
                            net::URLRequestContextGetter* request_context,
                            const FinishedCallback& callback)
     : callback_(callback), weak_ptr_factory_(this) {
   base::FilePath path = GetPopularSitesPath(profile, filename);
+  // Re-download the file once on every Chrome startup, but use the cached
+  // local file afterwards.
+  static bool overwrite = true;
   downloader_.reset(new FileDownloader(
-      GetPopularSitesURL(profile, filename), path, request_context,
+      GetPopularSitesURL(profile, filename), path, overwrite, request_context,
       base::Bind(&PopularSites::OnDownloadDone, base::Unretained(this), path)));
+  overwrite = false;
 }
 
 PopularSites::~PopularSites() {}
 
 void PopularSites::OnDownloadDone(const base::FilePath& path, bool success) {
   if (success) {
     base::PostTaskAndReplyWithResult(
         BrowserThread::GetBlockingPool()->GetTaskRunnerWithShutdownBehavior(
             base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN).get(),
         FROM_HERE,
         base::Bind(&ReadAndParseJsonFile, path),
         base::Bind(&PopularSites::OnJsonParsed,
                    weak_ptr_factory_.GetWeakPtr()));
   } else {
     DLOG(WARNING) << "Download failed";
     callback_.Run(false);
   }
 
   downloader_.reset();
 }
 
 void PopularSites::OnJsonParsed(scoped_ptr<std::vector<Site>> sites) {
   if (sites)
     sites_.swap(*sites);
   else
     sites_.clear();
   callback_.Run(!!sites);
 }