Add OptionsUI and its handler for multiple displays.

chrome/browser/resources/options2/chromeos/display_options.css

+/* Copyright (c) 2012 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. */
+
+#display-options-displays-view-host {
+  padding: 20px;
+}
+
+#display-options-displays-view {
+  height: 300px;
+  position: relative;
+}
+
+#display-configurations {
+  border-top: 1px solid blue;
+  padding-top: 20px;
+  text-align: right;
+}
+
+.displays-display {
+  background-color: white;
+  border: dashed 1px;
+  position: absolute;
+  text-align: center;
+  vertical-align: middle;
+  z-index: 0;
+}
+
+.displays-primary {
+  border: solid 1px blue;
+}
+
+.displays-focused {
+  border: solid 2px;
+  z-index: 1;

[James Hawkins, 2012/06/20 16:21:03]

Why do you need to set the z-index?

[Jun Mukai, 2012/06/21 08:42:58]

Removed.  Thanks for pointing.  That was introduced once I allowed overlapping
rectangles.

+}