Chrome talks to Play to install WebAPKs.

chrome/browser/android/webapk/webapk_installer.h

Index: chrome/browser/android/webapk/webapk_installer.h
diff --git a/chrome/browser/android/webapk/webapk_installer.h b/chrome/browser/android/webapk/webapk_installer.h
index c24a66886f1d919d5d86d9a41f6c0baaeb25b304..ded0e0827a2c57b08ddf164ba32110d7a1d378a2 100644
--- a/chrome/browser/android/webapk/webapk_installer.h
+++ b/chrome/browser/android/webapk/webapk_installer.h
@@ -143,6 +143,12 @@ class WebApkInstaller : public net::URLFetcherDelegate {
   void SendRequest(std::unique_ptr<webapk::WebApk> request_proto,
                    const GURL& server_url);
 
+  // Called when the package name of the WebAPK is available and the install
+  // or update request goes through Play Store.

[pkotwicz, 2016/12/02 02:24:00]

How about: "and the install or update request should be handled by Google Play."

[Xi Han, 2016/12/02 20:45:37]

Done.

+  void InstallOrUpdateWebApkFromPlayStore(const std::string& package_name,
+                                          int version,
+                                          const std::string& token);
+
   // Called with the URL of generated WebAPK and the package name that the
   // WebAPK should be installed at.
   void OnGotWebApkDownloadUrl(const GURL& download_url,