Fix the disappearance of "Offline" chip from the LocationBar when navigating to a fragment.

chrome/browser/android/offline_pages/offline_page_tab_helper.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 CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_TAB_HELPER_H_
 #define CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_TAB_HELPER_H_
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
@@ skipping 17 matching lines @@
  public:
   ~OfflinePageTabHelper() override;
 
   const OfflinePageItem* offline_page() { return offline_page_.get(); }
   void SetOfflinePage(const OfflinePageItem& offline_page,
                       bool is_offline_preview);
 
   // Whether the page is an offline preview.
   bool is_offline_preview() const { return is_offline_preview_; }
 
+  // Returns provisional offline page since actual navigation does not happen
+  // during unit tests.
+  const OfflinePageItem* GetOfflinePageForTest() const;
+
  private:
   friend class content::WebContentsUserData<OfflinePageTabHelper>;
 
   explicit OfflinePageTabHelper(content::WebContents* web_contents);
 
   // Overridden from content::WebContentsObserver:
   void DidStartNavigation(
       content::NavigationHandle* navigation_handle) override;
   void DidFinishNavigation(
       content::NavigationHandle* navigation_handle) override;
 
   void SelectPageForOnlineURLDone(const OfflinePageItem* offline_page);
 
   // The cached copy of OfflinePageItem if offline page is loaded for current
   // tab. This can be used to by the Tab to synchronously ask about the offline
   // info.
   std::unique_ptr<OfflinePageItem> offline_page_;
+  // Potential new offline page copy. This is reset to nullptr at the start
+  // of every navigation and set by network request interceptor. If the
+  // interceptor decided to not use offline page for the navigation or was not
+  // even invoked (as in case with fragment navigation), this stays nullptr.
+  std::unique_ptr<OfflinePageItem> provisional_offline_page_;
 
   bool reloading_url_on_net_error_ = false;
 
   // Whether the page is an offline preview. Offline page previews are shown
   // when a user's effective connection type is prohibitively slow.
   bool is_offline_preview_;
 
   base::WeakPtrFactory<OfflinePageTabHelper> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(OfflinePageTabHelper);
 };
 
 }  // namespace offline_pages
 
 #endif  // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_OFFLINE_PAGE_TAB_HELPER_H_