Refactors offline page tab helper to stash the offline page item on redirect.

chrome/browser/android/offline_pages/offline_page_utils.h

 // Copyright 2015 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 CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_UTILS_H_
 #define CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_UTILS_H_
 
 #include <stdint.h>
 
 #include "base/callback.h"
 
 class GURL;
 
 namespace content {
 class BrowserContext;
+class WebContents;
 }
 
 namespace offline_pages {
 struct OfflinePageItem;
 
 class OfflinePageUtils {
  public:
   // Returns true if |url| might point to an offline page.
   static bool MightBeOfflineURL(const GURL& url);
 
@@ skipping 25 matching lines @@
                             const GURL& offline_url);
 
   // Checks whether offline page for |online_url| exists.
   static bool HasOfflinePageForOnlineURL(
       content::BrowserContext* browser_context,
       const GURL& online_url);
 
   // Marks that the offline page related to the |offline_url| has been accessed.
   static void MarkPageAccessed(content::BrowserContext* browser_context,
                                const GURL& offline_url);
+
+  // Gets the offline page corresponding to the given web contents.  The
+  // returned pointer is owned by the web_contents and may be deleted by user
+  // navigation, so it is unsafe to store a copy of the returned pointer.
+  static const OfflinePageItem* GetCurrentOfflinePage(
+      content::WebContents* web_contents);
+
+  // Sets the offline page corresponding to the given web contents.  If
+  // |offline_page| contains |nullptr|, removes the page from the web contents.
+  static void SetCurrentOfflinePage(content::WebContents* web_contents,
+                                    const OfflinePageItem* offline_page);
 };
 
 }  // namespace offline_pages
 
 #endif  // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_UTILS_H_