Popular sites on the NTP

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"
+#include "base/path_service.h"
+#include "base/task_runner_util.h"
+#include "base/values.h"
+#include "chrome/browser/android/file_downloader.h"
+#include "chrome/common/chrome_paths.h"
+#include "content/public/browser/browser_thread.h"
+#include "url/gurl.h"
+
+using content::BrowserThread;
+
+namespace {
+
+const char kPopularSitesFilename[] = "ntp-popular-sites.json";
+const char kPopularSitesURL[] =
+    "https://www.gstatic.com/chrome/ntp/prototype0.json";

[Bernhard Bauer, 2015/08/03 17:04:51]

How about giving this a name that mentions popular sites?

[Marc Treib, 2015/08/04 08:16:41]

popular_sites_IN.json? -> out-of-band discussion

+
+base::FilePath GetPopularSitesPath() {
+  base::FilePath dir;
+  PathService::Get(chrome::DIR_USER_DATA, &dir);
+  return dir.AppendASCII(kPopularSitesFilename);
+}
+
+scoped_ptr<std::vector<PopularSites::Site>> ReadAndParseJsonFile(
+    const base::FilePath& path) {
+  scoped_ptr<std::vector<PopularSites::Site>> sites(
+      new std::vector<PopularSites::Site>);

[Bernhard Bauer, 2015/08/03 17:04:50]

Allocate the new vector after you've verified that the file is readable and can
be parsed? Otherwise you'll return an empty vector, which will not trigger the
failure code path.

[Marc Treib, 2015/08/04 08:16:41]

Done.

+
+  std::string json;
+  if (!base::ReadFileToString(path, &json)) {
+    DLOG(WARNING) << "Failed reading file";
+    return sites.Pass();
+  }
+
+  scoped_ptr<base::Value> value =
+      base::JSONReader::Read(json, base::JSON_ALLOW_TRAILING_COMMAS);
+  base::ListValue* list;
+  if (!value || !value->GetAsList(&list)) {
+    DLOG(WARNING) << "Failed parsing json";
+    return sites.Pass();
+  }
+
+  for (size_t i = 0; i < list->GetSize(); i++) {
+    base::DictionaryValue* item;
+    if (!list->GetDictionary(i, &item))
+      continue;
+    std::string title;
+    std::string url;
+    if (!item->GetString("title", &title) || !item->GetString("url", &url))
+      continue;
+    sites->push_back(PopularSites::Site(title, url));
+  }
+
+  return sites.Pass();
+}
+
+}  // namespace
+
+PopularSites::Site::Site(const std::string& title, const std::string& url)
+    : title(title), url(url) {}
+
+PopularSites::PopularSites(net::URLRequestContextGetter* request_context,
+                           const FinishedCallback& callback)
+    : callback_(callback), weak_ptr_factory_(this) {
+  base::FilePath path = GetPopularSitesPath();
+  downloader_.reset(new FileDownloader(
+      GURL(kPopularSitesURL), path, request_context,
+      base::Bind(&PopularSites::OnDownloadDone, base::Unretained(this), path)));
+}
+
+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);

[Bernhard Bauer, 2015/08/03 17:04:50]

That's Java style 😃 Chromium C++ style is to put the body on a new line.

[Marc Treib, 2015/08/04 08:16:41]

Done.

+  callback_.Run(!!sites);
+}