Load live version when reloading an offline page on connected network

components/offline_pages/request_header/offline_page_header.h

+// 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.
+
+#ifndef COMPONENTS_OFFLINE_PAGES_REQUEST_HEADER_OFFLINE_PAGE_HEADER_H_
+#define COMPONENTS_OFFLINE_PAGES_REQUEST_HEADER_OFFLINE_PAGE_HEADER_H_
+
+#include <string>
+
+namespace offline_pages {
+
+// Header that defines the custom behavior to load offline pages. Its value is a
+// comma/space separated name-value pair.
+extern const char kOfflinePageHeader[];
+
+// The name used in name-value pair of kOfflinePageHeader to tell if the offline
+// info in this header should be persisted across session restore.
+extern const char kOfflinePageHeaderPersistKey[];
+
+// The name used in name-value pair of kOfflinePageHeader to denote the reason
+// for loading offline page.
+extern const char kOfflinePageHeaderReasonKey[];
+// Possible values in name-value pair that denote the reason for loading offline
+// page.
+// The offline page should be loaded even when the network is connected. This is
+// because the live version failed to load due to certain net error.
+extern const char kOfflinePageHeaderReasonValueDueToNetError[];
+// The offline page should be loaded because the user clicks to open the
+// downloaded page explicitly.
+extern const char kOfflinePageHeaderReasonValueFromDownload[];
+// This only happens after the offline page is loaded due to above reason and
+// then the user reload current page. The network condition should be checked
+// this time to decide if a live version should be tried again.
+extern const char kOfflinePageHeaderReasonValueReload[];
+
+// The name used in name-value pair of kOfflinePageHeader to denote the offline
+// ID of the offline page to load.
+extern const char kOfflinePageHeaderIDKey[];
+
+// Used to parse the extra request header string that defines offline page
+// loading behaviors.
+struct OfflinePageHeader {
+ public:
+  enum class Reason {
+    NONE,
+    NET_ERROR,
+    DOWNLOAD,
+    RELOAD
+  };
+
+  OfflinePageHeader();
+
+  // Constructed from a request header value string.
+  // The struct members will be cleared if the parsing failed.
+  explicit OfflinePageHeader(const std::string& header_value);
+
+  ~OfflinePageHeader();
+
+  // Returns the full header string, including both key and value, that could be
+  // passed to set extra request header.
+  std::string GetCompleteHeaderString() const;
+
+  void Clear();
+
+  // Set if failed to parse a request header value string. For testing only.
+  bool did_fail_parsing_for_test;
+
+  // Flag to indicate if the header should be persisted across session restore.
+  bool need_to_persist;
+
+  // Describes the reason to load offline page.
+  Reason reason;
+
+  // The offline ID of the page to load.
+  std::string id;
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_REQUEST_HEADER_OFFLINE_PAGE_HEADER_H_