Allow switching between extended and unified

chrome/browser/resources/options/chromeos/display_options.html

Index: chrome/browser/resources/options/chromeos/display_options.html
diff --git a/chrome/browser/resources/options/chromeos/display_options.html b/chrome/browser/resources/options/chromeos/display_options.html
index f4977399b31a60631f18aa247c71a4436846146f..1d2818ae58b8fd616dd43e7f10b01b9b27718b88 100644
--- a/chrome/browser/resources/options/chromeos/display_options.html
+++ b/chrome/browser/resources/options/chromeos/display_options.html
@@ -16,6 +16,14 @@
           </button>
           <button id="display-options-set-primary"
               class="display-options-button" i18n-content="setPrimary">
+          </button>
+        </div>
+        <div id="display-options-unified-desktop"
+            class="selected-display-option-row" hidden>
+          <div class="selected-display-option-title">

[Jun Mukai, 2015/05/20 02:47:49]

Can you put a comment for why this is empty?
<!-- intentionally blank for the title column space. -->

[oshima, 2015/05/20 06:40:01]

Done.

+          </div>
+          <input id="display-options-toggle-unified-desktop" type="checkbox">
+          <span i18n-content="enableUnifiedDesktop"></span>

[Jun Mukai, 2015/05/20 02:47:49]

label for="display-options-toggle-unified-desktop" instead of span, so that
clicking on the text also toggles the checkbox.

[oshima, 2015/05/20 06:40:01]

Changed to use label, although I followed the other example as suggested by
presubmit. (label for="" seems to be banned)

[Jun Mukai, 2015/05/20 07:34:20]

Oh, I didn't know that details.  Enclosing by <label> looks good.

         </div>
         <div class="selected-display-option-row">
           <div class="selected-display-option-title"