Offline pages using NQE 2G Slow

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 "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 base {
+class Time;
+}
+
 namespace content {
 class WebContents;
 }
 
 namespace offline_pages {
 
 struct OfflinePageItem;
 
 // Per-tab class to manage switch between online version and offline version.
 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,
                           std::string* tab_id) const = 0;
+    virtual base::Time Now() const = 0;

[Lei Zhang, 2016/07/28 20:41:52]

a) I'm not sure you can forward declare if it's returning an object. I thought
it only worked for pointers to the forward declared object.

b) https://google.github.io/styleguide/cppguide.html#Forward_Declarations at
some point decided to just include the header. (I didn't make the decision, but
that's what it says)

[RyanSturm, 2016/07/28 22:07:18]

Done. You're absolutely right. Time is included via offline_page_types.h, 
offline_page_item.h. This wouldn't compile without the actual header include.

   };
 
   // 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() { return offline_page_.get(); }
 
  private:
   friend class content::WebContentsUserData<OfflinePageTabHelper>;
   friend class OfflinePageTabHelperTest;
@@ skipping 33 matching lines @@
   // 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_;
+
   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_