When the kChromeUIScheme was made savable, it also broke the disabling of the

chrome/browser/browser.cc

 // Copyright (c) 2010 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.
 
 #include "chrome/browser/browser.h"
 
 #if defined(OS_WIN)
 #include <shellapi.h>
 #include <windows.h>
 #endif  // OS_WIN
@@ skipping 3254 matching lines @@
   command_updater_.UpdateCommandEnabled(IDC_VIEW_SOURCE,
       current_tab->controller().CanViewSource());
   // Instead of using GetURL here, we use url() (which is the "real" url of the
   // page) from the NavigationEntry because its reflects their origin rather
   // than the display one (returned by GetURL) which may be different (like
   // having "view-source:" on the front).
   NavigationEntry* active_entry = nc.GetActiveEntry();
   bool is_savable_url =
       SavePackage::IsSavableURL(active_entry ? active_entry->url() : GURL());
   command_updater_.UpdateCommandEnabled(IDC_SAVE_PAGE, is_savable_url);
-  command_updater_.UpdateCommandEnabled(IDC_ENCODING_MENU, is_savable_url &&
-      SavePackage::IsSavableContents(current_tab->contents_mime_type()));
   command_updater_.UpdateCommandEnabled(IDC_EMAIL_PAGE_LOCATION,
       current_tab->ShouldDisplayURL() && current_tab->GetURL().is_valid());
 
+  // Changing the encoding is not possible on Chrome-internal webpages.
+  bool is_chrome_internal = (active_entry ?
+      active_entry->url().SchemeIs(chrome::kChromeUIScheme) : false);
+  command_updater_.UpdateCommandEnabled(IDC_ENCODING_MENU,
+      !is_chrome_internal && SavePackage::IsSavableContents(
+          current_tab->contents_mime_type()));
+
   // Show various bits of UI
   // TODO(pinkerton): Disable app-mode in the model until we implement it
   // on the Mac. Be sure to remove both ifdefs. http://crbug.com/13148
 #if !defined(OS_MACOSX)
   command_updater_.UpdateCommandEnabled(IDC_CREATE_SHORTCUTS,
       web_app::IsValidUrl(current_tab->GetURL()));
 #endif
   UpdateZoomCommandsForTabState();
 }
 
@@ skipping 756 matching lines @@
 }
 
 bool Browser::IsPinned(TabContents* source) {
   int index = tabstrip_model_.GetIndexOfTabContents(source);
   if (index == TabStripModel::kNoTab) {
     NOTREACHED() << "IsPinned called for tab not in our strip";
     return false;
   }
   return tabstrip_model_.IsTabPinned(index);
 }