First pass at adding http/backend cache to NetLog

chrome/browser/resources/net_internals/main.css

 /*
 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.
 */
 
 * {
   box-sizing: border-box;
   -moz-box-sizing: border-box;
 }
@@ skipping 74 matching lines @@
 
 #eventsListTableBody .source_CONNECT_JOB {
   color: blue;
 }
 
 #eventsListTableBody .source_HOST_RESOLVER_IMPL_JOB,
 #eventsListTableBody .source_HOST_RESOLVER_IMPL_REQUEST {
   color: #308080;
 }
 
+#eventsListTableBody .source_DISK_CACHE_ENTRY {
+  color: gray;
+}
+
 #eventsListTableBody .source_SOCKET {
   color: purple;
 }
 
 #eventsListTableBody .source_INIT_PROXY_RESOLVER {
   color: green;
 }
 
 #eventsListTableBody .source_NONE {
   color: red;
@@ skipping 150 matching lines @@
   font-size: 100%;
   font-weight: bold;
 }
 
 /**
  * Styling for text indicating a potential problem or error state.
  */
 .warningText {
   color: red;
 }