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 indicates that the offline page should be loaded if it exists
+// regardless current network conditions. Its value is a comma/space separated
+// name-value pair that may provide reason or define custom behavior.
+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.
+extern const char kOfflinePageHeaderReasonValueDueToNetError[];
+extern const char kOfflinePageHeaderReasonValueFromDownload[];

[Dmitry Titov, 2016/09/16 21:37:23]

These two values shoudl be commented.

[jianli, 2016/09/16 23:08:48]

Done.

+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,
+    UNKNOWN
+  };
+
+  OfflinePageHeader();
+  ~OfflinePageHeader();
+
+  // Parses from the header value string.
+  bool ParseFromHeaderValue(const std::string& header_value);

[Dmitry Titov, 2016/09/16 21:37:23]

Why not just have an explicit ctor from a string? (in addition to a default one)

[jianli, 2016/09/16 23:08:48]

If we use an explicit ctor from a string, we need to expose something like
parsed_successfully(). For the case that default ctor is used, returning either
true or false for parsed_successfully is kind of confusing. We can expose
another state or change this to tri-state, but it will make the whole logic more
complicated. So I think introducing an explicit parsing method seems to be more
straightforward.

+
+  // Returns the full header string, including both key and value, that could be
+  // passed to set extra request header.
+  std::string ToFullHeaderString() const;

[Dmitry Titov, 2016/09/16 21:37:23]

GetCompleteHeaderString ?

[jianli, 2016/09/16 23:08:48]

Done.

+
+  void Clear();
+
+  // 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_