That area is called the status bar. Using the material theme, you can add this line to your styles xml to change the color.
<item name="android:colorPrimaryDark">@color/primary_dark</item>
Docs: https://developer.android.com/training/material/theme.html
To maintain compatibility, you should define your theme as such
<!-- extend one of the Theme.AppCompat themes -->
<style name="Theme.MyTheme" parent="Theme.AppCompat.Light">
<!-- customize the color palette -->
<item name="colorPrimary">@color/primary</item>
<item name="colorPrimaryDark">@color/primary_dark</item>
<item name="colorAccent">@color/accent</item>
</style>
Then add this dependency in your build.gradle file
dependencies {
compile 'com.android.support:appcompat-v7:21.0.+'
}
Docs: https://developer.android.com/training/material/compatibility.html
NOTE: While this will allow older devices to use the Material theme, it cannot modify the status bar color. See this blog post
There are a couple workarounds that people have come up with here