Include AdView library with gradle

Question

I have my android project, and this is my part of my gradle file as explained in tutorial here

buildscript {
    repositories {
        jcenter()
        maven {
            url "https://maven.google.com"
        }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.3'
    }
}
apply plugin: 'com.android.application'

repositories {
    jcenter()
    maven {
        url "https://maven.google.com"
    }
}

dependencies {
    compile project(':engine')
    compile project(':android')
    compile 'com.google.android.gms:play-services-ads:11.2.0'
}

However after doing this, I still can't seem to include AdView object. It just doesn't seem to import.