Add additional density enums to android:screenDensity attribute

            <enum name="hdpi" value="240" />

            <!-- An extra high density screen, approximately 320dpi. -->

            <enum name="xhdpi" value="320" />

            <!-- An extra extra high density screen, approximately 480dpi. -->

            <enum name="xxhdpi" value="480" />

            <!-- An extra extra extra high density screen, approximately 640dpi. -->

            <enum name="xxxhdpi" value="640" />

        </attr>

    </declare-styleable>

<pre>

&lt;<a href="#compatible-screens">compatible-screens</a>&gt;

    &lt;<a href="#screen">screen</a> android:<a href="#screenSize">screenSize</a>=["small" | "normal" | "large" | "xlarge"]

            android:<a href="#screenDensity">screenDensity</a>=["ldpi" | "mdpi" | "hdpi" | "xhdpi"] /&gt;

            android:<a href="#screenDensity">screenDensity</a>=["ldpi" | "mdpi" | "hdpi" | "xhdpi" | "xxhdpi" | "xxxhdpi"] /&gt;

    ...

</compatible-screens>

</pre>

            <li>{@code mdpi}</li>

            <li>{@code hdpi}</li>

            <li>{@code xhdpi}</li>

            <li>{@code xxhdpi}</li>

            <li>{@code xxxhdpi}</li>

          </ul>

          <p class="note"><strong>Note:</strong> This attribute currently does not accept

          {@code xxhdpi} as a valid value, but you can instead specify {@code 480}

          as the value, which is the approximate threshold for xhdpi screens.</p>

          <p>For information about the different screen densities, see <a

href="{@docRoot}guide/practices/screens_support.html#range">Supporting Multiple Screens</a>.</p>

        </dd>

<dt>example</dt>

<dd>

<p>If your application is compatible with only small and normal screens, regardless

of screen density, then you must specify eight different {@code <screen>} elements,

because each screen size has four different density configurations. You must declare each one of

of screen density, then you must specify twelve different {@code <screen>} elements,

because each screen size has six different density configurations. You must declare each one of

these; any combination of size and density that you do <em>not</em> specify is considered a screen

configuration with which your application is <em>not</em> compatible. Here's what the manifest

entry looks like if your application is compatible with only small and normal screens:</p>

        <screen android:screenSize="small" android:screenDensity="mdpi" />

        <screen android:screenSize="small" android:screenDensity="hdpi" />

        <screen android:screenSize="small" android:screenDensity="xhdpi" />

        <screen android:screenSize="small" android:screenDensity="xxhdpi" />

        <screen android:screenSize="small" android:screenDensity="xxxhdpi" />

        <!-- all normal size screens -->

        <screen android:screenSize="normal" android:screenDensity="ldpi" />

        <screen android:screenSize="normal" android:screenDensity="mdpi" />

        <screen android:screenSize="normal" android:screenDensity="hdpi" />

        <screen android:screenSize="normal" android:screenDensity="xhdpi" />

        <screen android:screenSize="normal" android:screenDensity="xxhdpi" />

        <screen android:screenSize="normal" android:screenDensity="xxxhdpi" />

    </compatible-screens>

    <application ... >

        ...