Chromecast: Gradle: package android.support.v7.media does not exist

Chromecast: Gradle: package android.support.v7.media does not exist

I'm running into a small issue while trying to build a sample Chromecast
app. I can't seem to resolve android.support.v7.media in order to use the
MediaRouteSelector class. My gradle file dependencies look like this:
dependencies { compile 'com.android.support:support-v4:18.0.0' compile
files('libs/GoogleCastSdkAndroid.jar') }
and the only v7 lib I have in my sdk folder is for a gallery grid. Anyone
happen to know where I can find this lib, or what line I need to add to my
build file in order to find the correct package?
Thank you!