Add "Show saved copy" button in dino page when there's offline copy

chrome/common/render_messages.h

Index: chrome/common/render_messages.h
diff --git a/chrome/common/render_messages.h b/chrome/common/render_messages.h
index e096a931ac55f5f02da1eea0fb22de14d0c6336d..5083a0e4da31a309145caf08ccad6db102a3bcd4 100644
--- a/chrome/common/render_messages.h
+++ b/chrome/common/render_messages.h
@@ -323,10 +323,10 @@ IPC_MESSAGE_ROUTED1(ChromeViewMsg_SetCanShowNetworkDiagnosticsDialog,
                     bool /* can_show_network_diagnostics_dialog */)
 
 #if defined(OS_ANDROID)
-// Tells the renderer whether or not an offline page exists. This is used to
-// decide if "show saved pages" button will be provided on certain error page.
-IPC_MESSAGE_ROUTED1(ChromeViewMsg_SetHasOfflinePages,
-                    bool /* has_offline_pages */)
+// Tells the renderer about the status of the offline pages. This is used to
+// decide if offline related button will be provided on certain error page.
+IPC_MESSAGE_ROUTED1(ChromeViewMsg_SetOfflinePageInfo,
+                    int /* offline_page_status */)
 #endif
 
 // Provides the information needed by the renderer process to contact a
@@ -345,6 +345,11 @@ IPC_MESSAGE_ROUTED1(ChromeViewHostMsg_RunNetworkDiagnostics,
 // Message sent from the renderer to the browser to show the UI for offline
 // pages.
 IPC_MESSAGE_ROUTED0(ChromeViewHostMsg_ShowOfflinePages)
+
+// Message sent from the renderer to the browser to load the offline copy of
+// the page that fails to load due to no internet.
+IPC_MESSAGE_ROUTED1(ChromeViewHostMsg_LoadOfflineCopy,
+                    GURL /* url */)

[dcheng, 2015/11/13 19:40:25]

Since the renderer controls this parameter, doesn't this mean it can load the
offline copy for any page? Are there any security implications to this? From the
design, it looks like we plan on using MHTML right now (which can't run scripts
for security reasons).

[jianli, 2015/11/13 22:32:13]

Yes, the renderer could send the IPC to load the offline page, but only the
error page handler has the logic to do that, not any other pages.

Yes, we're using MHTML which does not support running scripts.

 #endif

[dcheng, 2015/11/13 19:40:25]

Can we add an // defined(OS_ANDROID) comment here?

[jianli, 2015/11/13 22:32:13]

Done.

 
 //-----------------------------------------------------------------------------