According to Google :
Search is one of the biggest drivers of app installs in the Play Store.
Improved conversion tracking for Android:
Introducing Android first app opens, a new conversion tracking solution that measures when a user first opens an app after clicking on an ad and completing an Android app install. In addition to providing app conversion tracking across Search, Display and YouTube, this new solution also allows developers to better align the conversion volume they see in AdWords with the data they see in a third-party measurement solution. First app opens are the standard conversion type for third-party solutions, so we’re working with key partners like Tune, AppsFlyer, Kochava, Adjust and Apsalar to ensure data consistency and give developers the freedom to use reporting and optimization features across AdWords and third-party solutions of their choice.
An even easier way to scale your app install ads across Google networks
In a few weeks, Universal App Campaigns will make it even easier to promote your apps on Google Play and across all Google properties, including: Search, YouTube, the AdMob in-app network, and the 2M+ sites on the Google Display Network. Simply let us know what your ad will say, who you want to reach, your budget and target cost-per-install, and we’ll do the rest.
In the coming weeks, a limited set of users will begin to see ads from a pilot group of advertisers who are already running Google search ads for their apps.