Add option to disallow the discarding of a tab that was previously discarded.

chrome/browser/ui/webui/about_ui.cc

Index: chrome/browser/ui/webui/about_ui.cc
diff --git a/chrome/browser/ui/webui/about_ui.cc b/chrome/browser/ui/webui/about_ui.cc
index 11e32fa7527c366240a3d157626a7e52f2862ac3..6c96c333b639f666632176d5225b07723c04395c 100644
--- a/chrome/browser/ui/webui/about_ui.cc
+++ b/chrome/browser/ui/webui/about_ui.cc
@@ -529,6 +529,8 @@ std::vector<std::string> GetHtmlTabDescriptorsForDiscardPage() {
                                 chrome::kChromeUIDiscardsURL,
                                 kAboutDiscardsRunCommand, it->tab_contents_id);
     }
+    str += base::StringPrintf("&nbsp;&nbsp;(%d discards this session)",
+                              it->discard_count);
     titles.push_back(str);
   }
   return titles;