Adding the chrome://copresence page

chrome/browser/resources/copresence.css

+/* Copyright 2014 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. */
+
+body {
+  background-color: white;

[xiyuan, 2014/12/05 18:56:55]

nit: not necessary, default bg color is white.

[Charlie, 2014/12/05 21:26:08]

Done.

+  color: black;
+  font-family: Helvetica,Arial,sans-serif;
+  font-size: 10pt;
+  margin: 10px 20px;
+}
+
+section {
+  margin-top: 50px;
+}
+
+table {
+  border: 1px solid DarkGrey;
+  border-spacing: 0;
+}
+
+thead {
+  background-color: rgb(220, 240, 255);
+  font-weight: bold;
+}
+
+tbody {
+  border-top: 1px solid DarkGrey;
+  height: 200px;
+  overflow-x: hidden;
+  overflow-y: scroll;
+}
+
+td {
+  padding: 5px;
+  text-align: left;
+}
+
+#directives-table td {
+  width: 200px;
+}
+
+#sent-tokens-table td,
+#received-tokens-table td {
+  width: 150px;
+}
+
+tbody,
+thead > tr {
+  display: block;
+}