Introduce content::PageState (again).

content/public/common/page_state.h

+// Copyright (c) 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.
+
+#ifndef CONTENT_PUBLIC_COMMON_PAGE_STATE_H_
+#define CONTENT_PUBLIC_COMMON_PAGE_STATE_H_
+
+#include <string>
+#include <vector>
+
+#include "content/common/content_export.h"
+
+class GURL;
+
+namespace base {
+class FilePath;
+}
+
+namespace content {
+
+// The PageState class represents the information needed by the rendering
+// engine to reconstruct a web page (and its tree of frames), including for
+// example the URLs of the documents and the values of any form fields.  This
+// information is used when navigating back & forward through session history.
+//
+// The browser process only sees the encoded form of the data, which is
+// designed as an archival format.  The renderer process can decode the data
+// using methods found in public/renderer/history_item_serialization.h.
+class CONTENT_EXPORT PageState {
+ public:
+  static PageState CreateFromEncodedData(const std::string& data);
+  static PageState CreateFromURL(const GURL& url);
+
+  static PageState CreateForTesting(
+      const GURL& url,
+      bool body_contains_password_data,
+      const char* optional_body_data,
+      const base::FilePath* optional_body_file_path);
+
+  PageState();
+
+  bool IsValid() const;
+  bool Equals(const PageState& page_state) const;
+  const std::string& ToEncodedData() const;
+
+  std::vector<base::FilePath> GetReferencedFiles() const;
+  PageState RemovePasswordData() const;
+  PageState RemoveScrollOffset() const;
+
+ private:
+  PageState(const std::string& data);
+
+  std::string data_;
+};
+
+// Support DCHECK_EQ(a, b), etc.
+inline bool operator==(const PageState& a, const PageState& b) {
+  return a.Equals(b);
+}
+inline bool operator!=(const PageState& a, const PageState& b) {
+  return !(a == b);
+}
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_COMMON_PAGE_STATE_H_