修改Actionbar菜单字体大小

<application
android:name=".MyApplication"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme">

<!-- Base application theme. -->
<style name="AppTheme" parent="BaseTheme">
<item name="android:actionMenuTextAppearance">@style/MenuTextStyle</item>
</style>

<style name="MenuTextStyle">
<item name="android:textSize">18sp</item>
</style>