code: function addDependencies(buildGradle) {
    // find the known line to match
    var match = buildGradle.match(/^(\s*)classpath 'com.android.tools.build(.*)/m);
    var whitespace = match[1];
    
    // modify the line to add the necessary dependencies
    var googlePlayDependency = whitespace + 'classpath \'com.google.gms:google-services:4.2.0\' // google-services dependency from cordova-plugin-firebase';
    var fabricDependency = whitespace + 'classpath \'io.fabric.tools:gradle:1.25.4\' // fabric dependency from cordova-plugin-firebase'
    var modifiedLine = match[0] + '\n' + googlePlayDependency + '\n' + fabricDependency;
    
    // modify the actual line
    return buildGradle.replace(/^(\s*)classpath 'com.android.tools.build(.*)/m, modifiedLine);
  }
docs: /*
  Added a dependency on 'com.google.gms' based on the position of the know 'com.android.tools.build' dependency in the build.gradle