Surface button for loading stale cache copy on net error page.

chrome/renderer/net/net_error_helper_core.h

 // Copyright 2013 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_RENDERER_NET_NET_ERROR_HELPER_CORE_H_
 #define CHROME_RENDERER_NET_NET_ERROR_HELPER_CORE_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 21 matching lines @@
   enum FrameType {
     MAIN_FRAME,
     SUB_FRAME,
   };
 
   enum PageType {
     NON_ERROR_PAGE,
     ERROR_PAGE,
   };
 
+  enum Button {
+    NO_BUTTON,
+    RELOAD_BUTTON,
+    LOAD_STALE_BUTTON,
+    MORE_BUTTON,
+  };
+
   // The Delegate handles all interaction with the RenderView, WebFrame, and
   // the network, as well as the generation of error pages.
   class Delegate {
    public:
     // Generates an error page's HTML for the given error.
     virtual void GenerateLocalizedErrorPage(
         const blink::WebURLError& error,
         bool is_failed_post,
         scoped_ptr<LocalizedError::ErrorPageParams> params,
+        bool* reload_button_shown,
+        bool* load_stale_button_shown,
         std::string* html) const = 0;
 
     // Loads the given HTML in the main frame for use as an error page.
     virtual void LoadErrorPageInMainFrame(const std::string& html,
                                           const GURL& failed_url) = 0;
 
     // Create extra Javascript bindings in the error page.
-    virtual void EnableStaleLoadBindings(const GURL& page_url) = 0;
+    virtual void EnablePageHelperFunctions() = 0;
 
     // Updates the currently displayed error page with a new error code.  The
     // currently displayed error page must have finished loading, and must have
     // been generated by a call to GenerateLocalizedErrorPage.
     virtual void UpdateErrorPage(const blink::WebURLError& error,
                                  bool is_failed_post) = 0;
 
     // Fetches an error page and calls into OnErrorPageFetched when done.  Any
     // previous fetch must either be canceled or finished before calling.  Can't
     // be called synchronously after a previous fetch completes.
     virtual void FetchNavigationCorrections(
         const GURL& navigation_correction_url,
         const std::string& navigation_correction_request_body) = 0;
 
     // Cancels fetching navigation corrections.  Does nothing if no fetch is
     // ongoing.
     virtual void CancelFetchNavigationCorrections() = 0;
 
     // Starts a reload of the page in the observed frame.
     virtual void ReloadPage() = 0;
 
+    // Load the original page from cache.
+    virtual void LoadPageFromCache(const GURL& page_url) = 0;
+
    protected:
     virtual ~Delegate() {}
   };
 
   explicit NetErrorHelperCore(Delegate* delegate);
   ~NetErrorHelperCore();
 
   // Examines |frame| and |error| to see if this is an error worthy of a DNS
   // probe.  If it is, initializes |error_strings| based on |error|,
   // |is_failed_post|, and |locale| with suitable strings and returns true.
@@ skipping 48 matching lines @@
   }
 
   int auto_reload_count() const { return auto_reload_count_; }
 
   bool ShouldSuppressErrorPage(FrameType frame_type, const GURL& url);
 
   void set_timer_for_testing(scoped_ptr<base::Timer> timer) {
     auto_reload_timer_.reset(timer.release());
   }
 
+  // Execute the effect of pressing the specified button.
+  // Note that the visual effects of the 'MORE' button are taken
+  // care of in JavaScript.
+  void ExecuteButtonPress(Button button);
+
  private:
   struct ErrorPageInfo;
 
   // Updates the currently displayed error page with a new error based on the
   // most recently received DNS probe result.  The page must have finished
   // loading before this is called.
   void UpdateErrorPage();
 
   void GenerateLocalErrorPage(
       FrameType frame_type,
@@ skipping 30 matching lines @@
   GURL search_url_;
 
   bool auto_reload_enabled_;
   scoped_ptr<base::Timer> auto_reload_timer_;
 
   // Is the browser online?
   bool online_;
 
   int auto_reload_count_;
   bool can_auto_reload_page_;
+
+  // Non-NO_BUTTON only when a navigation has been initiated from the error

[jar (doing other things), 2014/04/21 23:48:19]

nit: I couldn't parse the comment without working hard (the double negative hurt
me a tad).  Perhaps better would be:

|navigation_from_button_| is true when RELOAD, LOAD_STALE, or MORE _BUTTON was
pressed.  It is used to detect when such navigations result in errors.

[Randy Smith (Not in Mondays), 2014/04/22 20:40:02]

That doesn't quite capture what I'm going for, but I gave something else a try. 
Let me know what you think.

+  // page.  Used to detect when such navigations result in errors.
+  Button navigation_from_button_;
 };
 
 #endif  // CHROME_RENDERER_NET_NET_ERROR_HELPER_CORE_H_