[net] Add an informational bubble to about:net-internals#proxy when using a single SOCKS v5 proxy s…

chrome/browser/resources/net_internals/proxy_view.html

Index: chrome/browser/resources/net_internals/proxy_view.html
diff --git a/chrome/browser/resources/net_internals/proxy_view.html b/chrome/browser/resources/net_internals/proxy_view.html
index 52ac3969a66f0ae59f0fcb1cf831d73bf0f0d4bd..ec5158b79961be950f326aae9515ae5ed1b8d3a7 100644
--- a/chrome/browser/resources/net_internals/proxy_view.html
+++ b/chrome/browser/resources/net_internals/proxy_view.html
@@ -7,6 +7,15 @@
   font-size: 85%;
 }
 
+#proxy-view-socks-hints {
+  border: 1px solid orange;
+  padding: 1ex;
+}
+
+#proxy-view-socks-hints-flag {
+  margin: 1ex;
+}
+
 </style>
 
 <div id=proxy-view-tab-content class=content-box>
@@ -31,6 +40,13 @@
 
   </tr></table>
 
+  <div id=proxy-view-socks-hints>
+    Note that some traffic such as DNS prefetching will NOT go through the proxy
+    server. To prevent the browser from doing local DNS resolves try adding this
+    command line flag:
+    <pre id=proxy-view-socks-hints-flag></pre>
+  </div>
+
   <h4>
     Recently failed proxies, marked as bad
     <input type=button value="Clear bad proxies" id=proxy-view-clear-bad-proxies class="hide-when-not-capturing">