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

chrome/renderer/resources/neterror.css

Index: chrome/renderer/resources/neterror.css
diff --git a/chrome/renderer/resources/neterror.css b/chrome/renderer/resources/neterror.css
index 29c8dc2d8d157038a2301a0dc6f88e851e46c6a5..d364ffdc3c9211c6c780f3051d681844cc715bb0 100644
--- a/chrome/renderer/resources/neterror.css
+++ b/chrome/renderer/resources/neterror.css
@@ -72,6 +72,11 @@ a {
   margin: 20px;
 }
 
+.gray-button {
+  background: #d9d9d9;
+  color: #696969;
+}
+
 #help-box-inner {
   background-color: #f9f9f9;
   border-top: 1px solid #EEE;
@@ -452,4 +457,4 @@ html[subframe] body {
   button {
     width: auto;
   }
-}
+}