[Offlining] Updates the tab helper to use the async OfflinePageModel API

chrome/browser/android/offline_pages/offline_page_tab_helper.h

Index: chrome/browser/android/offline_pages/offline_page_tab_helper.h
diff --git a/chrome/browser/android/offline_pages/offline_page_tab_helper.h b/chrome/browser/android/offline_pages/offline_page_tab_helper.h
index f14aec4ab0de02dd793c51f67dfe293c9f2788cf..b63505107fe6f63bfd09cec8fcb4f18ddc09fc8c 100644
--- a/chrome/browser/android/offline_pages/offline_page_tab_helper.h
+++ b/chrome/browser/android/offline_pages/offline_page_tab_helper.h
@@ -27,6 +27,8 @@ class OfflinePageTabHelper :
  private:
   friend class content::WebContentsUserData<OfflinePageTabHelper>;
   friend class OfflinePageTabHelperTest;
+  FRIEND_TEST_ALL_PREFIXES(OfflinePageTabHelperTest,
+                           NewNavigationCancelsPendingRedirects);
 
   explicit OfflinePageTabHelper(content::WebContents* web_contents);
 
@@ -36,6 +38,12 @@ class OfflinePageTabHelper :
   void DidFinishNavigation(
       content::NavigationHandle* navigation_handle) override;
 
+  void GotRedirectURLForSupportedErrorCode(ui::PageTransition transition,
+                                           const GURL& from_url,
+                                           const GURL& redirect_url);
+  void GotRedirectURLForStartedNavigation(const GURL& from_url,
+                                          const GURL& redirect_url);
+
   void Redirect(const GURL& from_url, const GURL& to_url);
 
   base::WeakPtrFactory<OfflinePageTabHelper> weak_ptr_factory_;