Persist offline page info in a navigation entry if needed

chrome/browser/android/offline_pages/offline_page_info_handler.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/android/offline_pages/offline_page_info_handler.h"
+
+#include "base/strings/string_util.h"
+#include "components/offline_pages/request_header/offline_page_header.h"
+#include "components/sessions/content/content_serialized_navigation_driver.h"
+#include "content/public/browser/navigation_entry.h"
+
+namespace offline_pages {
+
+namespace {
+const char kOfflinePageInfoKey[] = "offline";
+}
+
+// static
+void OfflinePageInfoHandler::Register() {
+  std::unique_ptr<OfflinePageInfoHandler> instance(new OfflinePageInfoHandler);
+  sessions::ContentSerializedNavigationDriver::GetInstance()
+      ->RegisterExtendedInfoHandler(kOfflinePageInfoKey, std::move(instance));
+}
+
+OfflinePageInfoHandler::OfflinePageInfoHandler() {}
+
+OfflinePageInfoHandler::~OfflinePageInfoHandler() {}
+
+std::string OfflinePageInfoHandler::GetExtendedInfo(
+    const content::NavigationEntry& entry) const {
+  std::string extra_headers = entry.GetExtraHeaders();
+  if (extra_headers.empty())
+    return std::string();
+
+  // The offline header will be the only extra header if it is present.
+  std::string offline_header_key(offline_pages::kOfflinePageHeader);
+  offline_header_key += ": ";
+  if (!base::StartsWith(extra_headers, offline_header_key,
+                        base::CompareCase::INSENSITIVE_ASCII)) {
+    return std::string();
+  }
+  std::string header_value = extra_headers.substr(offline_header_key.length());
+  if (header_value.find("\n") != std::string::npos)
+    return std::string();
+
+  OfflinePageHeader header(header_value);
+  if (!header.need_to_persist)
+    return std::string();
+
+  return header_value;
+}
+
+void OfflinePageInfoHandler::RestoreExtendedInfo(
+    const std::string& info,
+    content::NavigationEntry* entry) {
+  OfflinePageHeader header(info);
+  // Some sanity check.
+  if (header.reason == OfflinePageHeader::Reason::NONE ||
+      !header.need_to_persist)
+    return;
+  entry->AddExtraHeaders(header.GetCompleteHeaderString());
+}
+
+}  // namespace offline_pages