Serve offline page for online URL on disconnected or bad networks

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"
-#include "components/offline_pages/offline_page_types.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 #include "url/gurl.h"
 
 namespace content {
 class WebContents;
 }
 
 namespace offline_pages {
 
 struct OfflinePageItem;
 
-// Per-tab class to manage switch between online version and offline version.
+// Per-tab class that monitors the navigations and stores the necessary info
+// to facilitate the synchronous access to offline information.
 class OfflinePageTabHelper :
     public content::WebContentsObserver,
     public content::WebContentsUserData<OfflinePageTabHelper> {
  public:
-  // Delegate that is used to better handle external dependencies.
-  // Default implementation is in .cc file, while tests provide an override.
-  class Delegate {
-   public:
-    virtual ~Delegate() {}
-    virtual bool GetTabId(content::WebContents* web_contents,
-                          int* tab_id) const = 0;
-    virtual base::Time Now() const = 0;
-  };
-
-  // This enum is used for UMA reporting. It contains all possible outcomes of
-  // redirect intent and result. Generally one of these outcomes will happen.
-  // The fringe errors (like no OfflinePageModel, etc.) are not reported due
-  // to their low probability.
-  // NOTE: because this is used for UMA reporting, these values should not be
-  // changed or reused; new values should be ended immediately before the MAX
-  // value. Make sure to update the histogram enum
-  // (OfflinePagesRedirectResult in histograms.xml) accordingly.
-  // Public for testing.
-  enum class RedirectResult {
-    REDIRECTED_ON_DISCONNECTED_NETWORK = 0,
-    PAGE_NOT_FOUND_ON_DISCONNECTED_NETWORK = 1,
-    // Flaky Network means the network reported an error when trying to fetch
-    // the resource.
-    REDIRECTED_ON_FLAKY_NETWORK = 2,
-    PAGE_NOT_FOUND_ON_FLAKY_NETWORK = 3,
-    IGNORED_FLAKY_NETWORK_FORWARD_BACK = 4,
-    REDIRECTED_ON_CONNECTED_NETWORK = 5,
-    NO_TAB_ID = 6,
-    SHOW_NET_ERROR_PAGE = 7,
-    REDIRECT_LOOP_OFFLINE = 8,
-    REDIRECT_LOOP_ONLINE = 9,
-    // Prohibitively slow means that the NetworkQualityEstimator reported a
-    // connection slow enough to warrant showing an offline page if available.
-    REDIRECTED_ON_PROHIBITIVELY_SLOW_NETWORK = 10,
-    PAGE_NOT_FOUND_ON_PROHIBITIVELY_SLOW_NETWORK = 11,
-    PAGE_NOT_FRESH_ON_PROHIBITIVELY_SLOW_NETWORK = 12,
-    REDIRECT_RESULT_MAX,
-  };
-
   ~OfflinePageTabHelper() override;
 
-  const OfflinePageItem* offline_page() const { return offline_page_.get(); }
+  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_; }
 
  private:
   friend class content::WebContentsUserData<OfflinePageTabHelper>;
-  friend class OfflinePageTabHelperTest;
-  FRIEND_TEST_ALL_PREFIXES(OfflinePageTabHelperTest,
-                           NewNavigationCancelsPendingRedirects);
 
   explicit OfflinePageTabHelper(content::WebContents* web_contents);
 
-  void SetDelegateForTesting(std::unique_ptr<Delegate> delegate);
-
   // Overridden from content::WebContentsObserver:
   void DidStartNavigation(
       content::NavigationHandle* navigation_handle) override;
   void DidFinishNavigation(
       content::NavigationHandle* navigation_handle) override;
 
-  void RedirectToOnline(const GURL& from_url,
-                        const OfflinePageItem* offline_page);
+  void SelectPageForOnlineURLDone(const OfflinePageItem* offline_page);
 
-  // 3 step redirection to the offline page. First getting all the pages, then
-  // selecting appropriate page to redirect to and finally attempting to
-  // redirect to that offline page, and caching metadata of that page locally.
-  // RedirectResult is accumulated along the codepath to reflect the overall
-  // result of redirection - and be reported to UMA at the end.
-  void GetBestPageForRedirectToOffline(RedirectResult result,
-                                       const GURL& online_url);
-  void SelectPageForOnlineURLDone(
-      RedirectResult result,
-      const GURL& online_url,
-      const OfflinePageItem* offline_page);
-  void TryRedirectToOffline(RedirectResult result,
-                            const GURL& from_url,
-                            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_;
 
-  void Redirect(const GURL& from_url, const GURL& to_url);
-
-  // Returns true if a given URL is in redirect chain already.
-  bool IsInRedirectLoop(const GURL& to_url) const;
-
-  void ReportRedirectResultUMA(RedirectResult result);
-
-  // Iff the tab we are associated with is redirected to an offline page,
-  // |offline_page_| will be non-null.  This can be used to synchronously ask
-  // about the offline state of the current web contents.
-  std::unique_ptr<OfflinePageItem> offline_page_;
-  std::unique_ptr<Delegate> delegate_;
+  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_