Add "SHOW ALL SAVED PAGES" button to offline error page

components/error_page/renderer/net_error_helper_core.h

Index: components/error_page/renderer/net_error_helper_core.h
diff --git a/components/error_page/renderer/net_error_helper_core.h b/components/error_page/renderer/net_error_helper_core.h
index 6a3dc7b86035182471273cf35137e5cceb40ac61..47810f591b21c3769aa1b7ba514fb4f7e49748c9 100644
--- a/components/error_page/renderer/net_error_helper_core.h
+++ b/components/error_page/renderer/net_error_helper_core.h
@@ -50,6 +50,7 @@ class NetErrorHelperCore {
     EASTER_EGG,
     SHOW_CACHED_COPY_BUTTON,  // "Google cached copy" button label experiment.
     DIAGNOSE_ERROR,
+    SHOW_SAVED_PAGES_BUTTON,
   };
 
   // The Delegate handles all interaction with the RenderView, WebFrame, and
@@ -61,10 +62,12 @@ class NetErrorHelperCore {
         const blink::WebURLError& error,
         bool is_failed_post,
         bool can_show_network_diagnostics_dialog,
+        bool has_offline_pages,
         scoped_ptr<ErrorPageParams> params,
         bool* reload_button_shown,
         bool* show_saved_copy_button_shown,
         bool* show_cached_copy_button_shown,
+        bool* show_saved_pages_button_shown,
         std::string* html) const = 0;
 
     // Loads the given HTML in the frame for use as an error page.
@@ -80,7 +83,8 @@ class NetErrorHelperCore {
     // been generated by a call to GenerateLocalizedErrorPage.
     virtual void UpdateErrorPage(const blink::WebURLError& error,
                                  bool is_failed_post,
-                                 bool can_show_network_diagnostics_dialog) = 0;
+                                 bool can_show_network_diagnostics_dialog,
+                                 bool has_offline_pages) = 0;
 
     // Fetches an error page and calls into OnErrorPageFetched when done.  Any
     // previous fetch must either be canceled or finished before calling.  Can't
@@ -108,6 +112,9 @@ class NetErrorHelperCore {
     // Run the platform diagnostics too for the specified URL.
     virtual void DiagnoseError(const GURL& page_url) = 0;
 
+    // Shows the UI for offline pages.
+    virtual void ShowOfflinePages() = 0;
+
    protected:
     virtual ~Delegate() {}
   };
@@ -169,6 +176,10 @@ class NetErrorHelperCore {
                                      const std::string& country_code,
                                      const std::string& api_key,
                                      const GURL& search_url);
+
+  // Notifies by the browser whether an offline page exists.
+  void OnSetHasOfflinePages(bool has_offline_pages);
+
   // Notifies |this| that the network's online status changed.
   // Handler for NetworkStateChanged notification from the browser process. If
   // the network state changes to online, this method is responsible for
@@ -279,6 +290,10 @@ class NetErrorHelperCore {
   // the error page.  It is used to detect when such navigations result
   // in errors.
   Button navigation_from_button_;
+
+  // Whether an offline page exists. This is used to decide if "Show saved
+  // pages" will be provided in certain error page.
+  bool has_offline_pages_;
 };
 
 }  // namespace error_page