base::Optional: Use anonymous union instead of base::AlignedMemory

styleguide/c++/c++11.html

Index: styleguide/c++/c++11.html
diff --git a/styleguide/c++/c++11.html b/styleguide/c++/c++11.html
index 6f1262b11a224cd0c1f3c1ee41fe3b527c2e9df8..1713042756d17056e2c56e25b7b04ad87e0d6076 100644
--- a/styleguide/c++/c++11.html
+++ b/styleguide/c++/c++11.html
@@ -276,6 +276,14 @@ template &lt;typename T&gt;<br/>void Function(T&& t) { ... }</code></td>
 </tr>
 
 <tr>
+<td>Union Class Members</td>
+<td><code>union <i>name</i> {<i>class</i> <i>var</i>}</code></td>
+<td>Allows class type members</td>
+<td><a href="http://en.cppreference.com/w/cpp/language/union">Union declarations</a></td>
+<td>Usage should be rare.</td>
+</tr>
+
+<tr>
 <td>Variadic Macros</td>
 <td><code>#define <i>MACRO</i>(...) <i>Impl</i>(<i>args</i>, __VA_ARGS__)</code></td>
 <td>Allows macros that accept a variable number of arguments</td>
@@ -675,14 +683,6 @@ work in all our compilers yet.</p>
 </tr>
 
 <tr>
-<td>Union Class Members</td>
-<td><code>union <i>name</i> {<i>class</i> <i>var</i>}</code></td>
-<td>Allows class type members</td>
-<td><a href="http://en.cppreference.com/w/cpp/language/union">Union declarations</a></td>
-<td></td>
-</tr>
-
-<tr>
 <td>User-Defined Literals</td>
 <td><code><i>type</i> <i>var</i> = <i>literal_value</i>_<i>type</i></code></td>
 <td>Allows user-defined literal expressions</td>